# Patent

## Title
Method and server for searching for data stream dividing point based on server

## Abstract

Embodiments of the present invention provide a method for searching for a data stream dividing point based on a server. In the embodiments of the present invention, a data stream dividing point is searched for by determining whether at least a part of data in a window of M windows meets a preset condition, and when the at least a part of data in the window does not meet the preset condition, a length of N*U is skipped, so as to obtain a next potential dividing point, thereby improving efficiency of searching for a data stream dividing point.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of International Application No. PCT/CN2014/072648, filed on Feb. 27, 2014, which claims priority to International Application No. PCT/CN2014/072115, filed on Feb. 14, 2014, both of which are hereby incorporated by reference in their entireties.


TECHNICAL FIELD
The present invention relates to the field of information technologies, and in particular, to a method and a server for searching for a data stream dividing point based on a server.
BACKGROUND
As data amounts keep growing, it becomes a critical challenge to provide sufficient data storage in the storage field currently. At present, a manner of addressing such a challenge is using a deduplication technology by means of a redundancy feature of data that needs to be stored, so as to reduce an amount of stored data.
In an algorithm of eliminating duplicate data based on a content defined chunk (CDC) in the prior art, a data stream to be stored is first divided into multiple data chunks. To divide a data stream into data chunks, a suitable dividing point needs to be found in the data stream, and data between two adjacent dividing points in the data stream forms one data chunk. A feature value of a data chunk is calculated, so as to find whether data chunks having a same feature value exist. If the data chunks having a same feature value are found, it is regarded that duplicate data exists. Specifically, in a technology of eliminating duplicate data based on a content defined chunk, a sliding window technique is applied to search for a dividing point of a chunk based on content of a file, that is, a Rabin fingerprint of data in a window is calculated to determine a data stream dividing point. It is assumed that a dividing point is searched for from left to right in a data stream. A fingerprint of data in a sliding window is calculated each time, and after a modulo operation is performed on a fingerprint value based on a given integer K, a result of the modulo operation is compared with a given remainder R. If the result of the modulo operation equals the given remainder R, the right end of the window is a data stream dividing point. Otherwise, the window continues to be slid rightward by one byte, and calculation and comparison are performed sequentially and cyclically until the end of the data stream is reached. In a process of eliminating duplicate data based on a content defined chunk, a large quantity of computing resources need to be consumed to search for a data stream dividing point, which therefore becomes a bottleneck in improving performance of eliminating duplicate data.
SUMMARY
According to a first aspect, an embodiment of the present invention provides a method for searching for a data stream dividing point based on a server, where a rule is preset on the server, where the rule is: for a potential dividing point k, determining M points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers; and the method includes:
(a) determining a point piz and a window Wiz[piz−Az, piz+Bz] corresponding to the point piz for a current potential dividing point ki according to the rule, where i and z are integers, and 1≦z≦M;
(b) determining whether at least a part of data in the window Wiz[piz−Az, piz+Bz] meets a preset condition Cz; and
when the at least a part of data in the window Wiz[piz−Az, piz+Bz] does not meet the preset condition Cz, skipping N minimum units U for searching for a data stream dividing point from the point piz along a direction of searching for a data stream dividing point, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥+∥(ki−pix)∥), so as to obtain a new potential dividing point, and performing step (a); and
(c) when at least a part of data in each window Wix[pix−Ax, pix+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, selecting the current potential dividing point ki as a data stream dividing point.
According to a second aspect, an embodiment of the present invention provides a method for searching for a data stream dividing point based on a server, where a rule is preset on the server, where the rule is: for a potential dividing point k determining M windows Wx[k−Ax, k+Bx], and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers; and
the method includes:
(a) determining a corresponding window Wiz[ki−Az, ki+Bz] for a current potential dividing point ki according to the rule, where i and z are integers, and 1≦z≦M;
(b) determining whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets a preset condition Cz; and
when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skipping N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along a direction of searching for a data stream dividing point, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a new potential dividing point, and performing step (a); and
(c) when at least a part of data in each window Wix[ki−Ax, ki+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, selecting the current potential dividing point ki as a data stream dividing point.
With reference to the second aspect, in a first possible implementation manner, the rule further includes that at least two windows Wie[ki−Ae, ki+Be] and Wif[ki−Af, ki+Bf] meet conditions |Ae+Be|=|Af+Bf| and Ce=Cf.
With reference to the first possible implementation manner of the second aspect, in a second possible implementation manner, the rule further includes that Ae and Af are positive integers.
With reference to the first possible implementation manner or the second possible implementation manner of the second aspect, in a third possible implementation manner, the rule further includes Ae−1=Af and Be+1=Bf.
With reference to the second aspect, or any one of the first to third possible implementation manners of the second aspect, in a fourth possible implementation manner, the determining whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz specifically includes:
determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.
With reference to the fourth possible implementation manner of the second aspect, in a fifth possible implementation manner, the determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz is specifically: determining, by using a hash function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.
With reference to the second aspect, or any one of the first to fifth possible implementation manners of the second aspect, in a sixth possible implementation manner, when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, the N minimum units U for searching for a data stream dividing point are skipped from the current potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and according to the rule, a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[ki−Az, ki+Bz] or a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point falls within a range of the window Wiz[ki−Az, ki+Bz], where the window Wic[ki−Ac, ki+Bc] determined for the new potential dividing point is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M windows that are determined for the new potential dividing point according to the rule.
With reference to the fourth possible implementation manner of the second aspect, in a seventh possible implementation manner, the determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz specifically includes:
selecting F bytes in the window Wiz[ki−Az, ki+Bz], and using the F bytes repeatedly H times to obtain F*H bytes in total, where F≧1, each byte is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the F*H bytes, bits corresponding to the F*H bytes can be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              
                F
                *
                H
              
              ,
              1
            
          
        
        
          
            a
            
              
                F
                *
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              
                F
                *
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




where when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1, where am,n represents any one of am,1, . . . , and am,8, a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the F*H bytes, the matrix Va is represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                F
                *
                H
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                F
                *
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                F
                *
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




F*H*8 random numbers are selected from random numbers following normal distribution to form a matrix R, the matrix R is represented as:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              
                F
                *
                H
              
              ,
              1
            
          
        
        
          
            h
            
              
                F
                *
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              
                F
                *
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers in an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8, Sa1, Sa2, . . . , and SaF*H are obtained in a same way, a quantity K of values greater than 0 among Sa1, Sa2, . . . , and SaF*H is counted, and when K is an even number, the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

In the embodiments of the present invention, a data stream dividing point is searched for by determining whether at least a part of data in a window of M windows meets a preset condition, and when the at least a part of data in the window does not meet the preset condition, a length of N*U is skipped, so as to obtain a next potential dividing point, thereby improving efficiency of searching for a data stream dividing point.



BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram of an application scenario according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a data stream dividing point;
FIG. 3 is a schematic diagram of searching for a data stream dividing point;
FIG. 4 is a schematic diagram of a method according to an embodiment of the present invention;
FIG. 5 and FIG. 6 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 7 and FIG. 8 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 9 and FIG. 10 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 11, FIG. 12, and FIG. 13 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 14 and FIG. 15 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 16 and FIG. 17 are schematic diagrams of determining whether at least a part of data in a window meets a preset condition;
FIG. 18 is a structural diagram of a deduplication server;
FIG. 19 is a structural diagram of a deduplication server;
FIG. 20 is a schematic diagram of a method according to an embodiment of the present invention;
FIG. 21 and FIG. 22 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 23 and FIG. 24 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 25 and FIG. 26 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 27, FIG. 28, and FIG. 29 are schematic diagrams of an implementation manner of searching for a data stream dividing point;
FIG. 30 and FIG. 31 are schematic diagrams of an implementation manner of searching for a data stream dividing point; and
FIG. 32 and FIG. 33 are schematic diagrams of determining whether at least a part of data in a window meets a preset condition.
FIG. 34 and FIG. 35 are schematic diagrams of probability that at least a part of data in a window meets a preset condition.



DESCRIPTION OF EMBODIMENTS
With ongoing progress of storage technologies, amounts of generated data grow increasingly, and a large amount of data has raised the highest requirement for storage capacity. Purchase costs of IT equipment increase along with storage capacity. To mitigate the demand conflict between the amounts of data and the storage capacity and lower purchase costs of IT equipment, a technology of eliminating duplicate data is introduced to the field of data storage.
A use scenario of an embodiment of the present invention is a data backup scenario. Data backup is a process of making, by using a backup server, a backup of data onto another storage medium to prevent data loss due to various reasons. FIG. 1 shows an architecture of a data backup system. The data backup system includes clients (101a, 101b, . . . , and 101n), a backup server 102, a duplicate data elimination server (referred to as a deduplication server or a duplication elimination server for short) 103, and storage devices (104a, 104b, . . . , and 104n). The clients (101a, 101b, . . . , and 101n) may be application servers, work stations or the like. The backup server 102 is configured to make a backup of data generated by the clients. The deduplication server 103 is configured to execute a task of eliminating duplicate data for backup data. The storage devices (104a, 104b, . . . , and 104n) serve as storage media that store data from which duplicate data has been eliminated, and may be storage media such as disk arrays and tape libraries. The clients (101a, 101b, . . . , and 101n), the backup server 102, the duplicate data elimination server 103, and the storage devices (104a, 104b, . . . , and 104n) may be connected in a manner such as by using a switch, a local area network, the Internet, or an optical fiber. The foregoing devices may be located at a same site, or may be located at different sites. The backup server 102, the duplication elimination server 103, and the storage devices (104a, 104b, . . . , and 104n) may be independent physical devices, or may be physically integrated into a whole in specific implementation, or the backup server 102 and the duplication elimination server 103 are integrated into a whole, or the duplication elimination server 103 and the storage devices (104a, 104b, . . . , and 104n) are integrated into a whole, or the like.
The deduplication server 103 performs an operation of eliminating duplicate data on a data stream of backup data, where the operation generally includes the following steps:
(1) searching for a data stream dividing point: searching for a data stream dividing point in a data stream according to a specific algorithm;
(2) performing division according to the found data stream dividing point to obtain data chunks;
(3) calculating a feature value of each data chunk: calculating the feature value of the data chunk, which serves as a feature for identifying the data chunk; and adding the feature value obtained by means of calculation to a data chunk feature list of a file corresponding to the data stream, where an SHA-1 or MD5 algorithm is generally used to calculate a feature value of a data chunk;
(4) detecting a same data chunk: comparing the feature value of the data chunk obtained by means of calculation with a feature value that already exists in the data chunk feature list to determine whether an identical data chunk exists; and
(5) eliminating duplicate data block: if it is found by detecting a same data chunk that a feature value the same as that of the data chunk exists in the data chunk feature list, skipping storage of the data chunk or determining whether to store the data chunk according to a storage quantity of duplicate data chunks that is determined according to a backup policy.
It can be known, from the step of performing, by the deduplication server 103, the operation of eliminating duplicate data on a data stream of backup data, that the search for a data stream dividing point, serving as a key step in the operation of eliminating duplicate data, directly determines performance of duplicate data elimination.
In an embodiment of the present invention, the deduplication server 103 receives a backup file sent by the backup server 102, and performs processing of eliminating duplicate data on the file. A backup file to be processed is usually presented in the form of a data stream on the deduplication server 103. When the deduplication server 103 searches for a dividing point in a data stream, a minimum unit for searching for a data stream dividing point usually needs to be determined. Specifically, as shown in FIG. 2, for example, a potential dividing point k1 is located between two consecutive minimum units, whose sequence numbers are 1 and 2, for searching for a data stream dividing point. A potential dividing point refers to a point for which it needs to be determined whether the point can serve as a data stream dividing point. When the point k1 is a data stream dividing point, in a direction of searching for a data stream dividing point shown by an arrow in FIG. 2, a next potential dividing point k7 is searched for, that is, a point located between two consecutive minimum units, whose sequence numbers are 7 and 8, for searching for a data stream dividing point. When the potential dividing point k7 is a data stream dividing point, data between the two adjacent data stream dividing points k1, and k7 is 1 data chunk. The minimum unit for searching for a data stream dividing point may specifically be determined according to an actual requirement, and here 1 byte is used as an example, that is, all the minimum units, whose sequence numbers are 1, 2, 7, and 8, for searching for a data stream dividing point have a size of 1 byte. The direction of searching for a data stream dividing point shown in FIG. 2 usually represents a search direction from a file header to a file trailer or a direction from a file trailer to a file header, and in this embodiment, the search direction from a file header to a file trailer is used as an example.
In a scenario of eliminating duplicate data, a smaller data chunk generally indicates a higher rate of eliminating duplicate data and an easier way to find a duplicate data chunk, but a larger amount of metadata generated from that; moreover, after a data chunk diminishes to a degree, the rate of eliminating duplicate data no longer increases, but the amount of metadata increases rapidly. Therefore, a size of a data chunk may be controlled. In actual applications, a minimum value of a data chunk, for example, 4 KB (4096 bytes), is usually set; in consideration of the rate of eliminating duplicate data at the same time, a maximum value of a data chunk is also set, that is, the size of a data chunk cannot exceed the maximum value, for example, 12 KB (12288 bytes). A specific implementation manner is shown in FIG. 3. The deduplication server 103 searches for a data stream dividing point along the direction shown by the arrow. ka is a currently found data stream dividing point, and from ka, a next potential dividing point is searched for in the direction of searching for a data stream dividing point. To meet the requirement of a minimum data chunk, usually starting from a data stream dividing point, a size of the minimum data chunk is skipped along a direction of searching for a data stream dividing point, and the search starts from an end position of the minimum data chunk, that is, the end position of the minimum data chunk serves as a next potential dividing point ki. In this embodiment of the present invention, a minimum data chunk of 4 KB, that is, 4*1024=4096 bytes may be first skipped from the point ka along the direction of searching for a data stream dividing point. 4096 bytes are skipped from the point ka along the direction of searching for a data stream dividing point, and the point ki is obtained at an end position of a 4096th byte to serve as a potential dividing point. For example, ki is located between two consecutive minimum units, whose sequence numbers are 4096 and 4097, for searching for a data stream dividing point. Still using FIG. 3 as an example, ka is a currently found data stream dividing point, and a next data stream dividing point is searched for along the direction shown in FIG. 3. If no next data stream dividing point is found after a maximum value of a data chunk is exceeded, starting from the point ka in the direction of searching for a data stream dividing point, a point kz at which the maximum value of a data chunk is reached serves as the next data stream dividing point and forced division is performed.
An embodiment of the present invention provides a method for searching for a data stream dividing point based on a deduplication server, which, as shown in FIG. 4, includes:
A rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining M points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers, where a distance between px and the potential dividing point k is dx minimum units for searching for a data stream dividing point, the minimum unit for searching for a data stream dividing point is represented as U, and in this embodiment, U=1 byte. In an implementation manner shown in FIG. 3, about a value of M, in one implementation manner, a value of M*U is not greater than a preset maximum distance between two adjacent data stream dividing points, that is, a preset maximum length of a data chunk. It is determined whether at least a part of data in a window Wz[pz−Az, pz+Bz] corresponding to a point pz meets a preset condition Cz, where, z is an integer, 1≦z≦M, and (pz−Az) and (pz+Bz) represent two boundaries of the window Wz. When it is determined that at least a part of data in a window Wz[pz−Az, pz+Bz] of any one point pz does not meet the preset condition Cz, N bytes are skipped from the point pz corresponding to the window Wz[pz−Az, pz+Bz] that does not meet the preset condition along a direction of searching for a data stream dividing point, where N≦∥Bz∥+maxx(∥Ax∥+∥(k−px)∥), where ∥(k−px)∥ represents a distance between any point of the M points px and the potential dividing point k, maxx∥Ax∥+∥(k−px)∥) represents a maximum value of a sum of an absolute value of the distance between the any point of the M points px and the potential dividing point k and an absolute value of Ax corresponding to the any point, and ∥Bz∥ represents an absolute value of Bz in Wz[pz−Az, pz+Bz]. A principle for setting a value of N is specifically introduced in the following embodiments. When it is determined that at least a part of data in each window Wx[px−Ax, px+Bx] of the M windows meets the preset condition Cx, the potential dividing point k is a data stream dividing point.
Specifically, for a current potential dividing point ki, the following steps are performed according to the rule:
Step 401: Determine a point piz and a window Wiz[piz−Az, piz+Bz] corresponding to the point piz for a current potential dividing point ki according to the rule, where i and z are integers, and 1≦z≦M.
Step 402: Determine whether at least a part of data in the window Wiz[piz−Az, piz+Bz] meets a preset condition Cz;
when the at least a part of data in the window Wiz[piz−Az, piz+Bz] does not meet the preset condition Cz, skip N minimum units U for searching for a data stream dividing point from the point piz along a direction of searching for a data stream dividing point, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥+∥(ki−pix)∥), so as to obtain a new potential dividing point, and perform step 401; and
when at least a part of data in each window Wix[pix−Ax, pix+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, select the current potential dividing point ki as a data stream dividing point.
Further, the rule further includes that at least two points pe and pf meet conditions Ae=Af, Be=Bf, and Ce=Cf.
The rule further includes: relative to the potential dividing point k, the at least two points pe and pf are in a direction opposite to the direction of searching for a data stream dividing point.
The rule further includes that a distance between the at least two points pe and pf is 1 U.
The determining whether at least a part of data in the window Wiz[piz−Az, piz+Bz] meets a preset condition Cz specifically includes:
determining, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz.
The determining, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz is specifically: determining, by using a hash function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz.
When the at least a part of data in the window Wiz[piz−Az, piz+Bz] does not meet the preset condition Cz, the N minimum units U for searching for a data stream dividing point are skipped from the point piz along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and according to the rule, a left boundary of a window Wic[pic−Ac, pic+Bc] corresponding to a point pic that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[piz−Az, piz+Bz] or a left boundary of a window Wic[pic−Ac, pic+Bc] corresponding to a point pic that is determined for the new potential dividing point falls within a range of the window Wiz[piz−Az, piz+Bz], where the point pic determined for the new potential dividing point is a point ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M points that are determined for the new potential dividing point according to the rule.
In this embodiment of the present invention, a data stream dividing point is searched for by determining whether at least a part of data in a window of M windows meets a preset condition, and when the at least a part of data in the window does not meet the preset condition, a length of N*U is skipped, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥+∥(ki−pix)∥), so as to obtain a next potential dividing point, thereby improving efficiency of searching for a data stream dividing point.
In a process of eliminating duplicate data, to ensure an even size of a data chunk, a size of an average data chunk (also referred to as an average chunk) is considered. That is, while limits on a size of a minimum data chunk and a size of a maximum data chunk are met, the size of the average data chunk is determined to ensure an even size of an obtained data chunk. A probability (represented as P(n)) of finding a data stream dividing point depends on two factors, that is, the quantity M of the points px and a probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets the preset condition Cx, where the former affects a length for skipping, the latter affects a probability of skipping, and the two together affect the size of the average chunk. Generally, when the size of the average chunk is fixed, as the quantity M of the points px increases, the probability that at least a part of data in a window Wx[px−Ax, px+Bx] corresponding to a single point px meets the preset condition Cx also increases. For example, the rule preset on the deduplication server 103 is: for a potential dividing point k, determining 11 points px, where x indicates consecutive natural numbers from 1 to 11 separately, and a probability that at least a part of data in a window Wx[px−Ax, px+Bx] corresponding to any point px of the 11 points meets the preset condition Cx is 1⁄2. Another group of rules preset on the deduplication server 103 is: selecting 24 points px for the potential dividing point k, where x indicates consecutive natural numbers from 1 to 24 separately, and a probability that at least a part of data in a window Wx[px−Ax, px+Bx] corresponding to any point px of the 24 points meets the preset condition Cx is 3⁄4. For the setting of a probability that at least a part of data in a specific window Wx[px−Ax, px+Bx] meets the preset condition Cx, reference may be made to the description of the part of determining whether the at least a part of data in the window Wx[px−Ax, px+Bx] meets the preset condition Cx. P(n) depends on the two factors, that is, the quantity M of points px and the probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets the preset condition Cx, and P(n) represents a probability that no data stream dividing point is found after n minimum units for searching for a data stream dividing point in a search from a start position/previous data stream dividing point of a data stream. A process of calculating P(n) that depends on the two factors is actually an n-step Fibonacci sequence, which is described below in detail. After P(n) is obtained, 1−P(n) is a distribution function of a data stream dividing point, and (1−P(n))−(1−P(n−1))=P(n−1)−P(n) is a probability that a data stream dividing point is found at an nth point, that is, a density function of a data stream dividing point. Integration




  
    ∑
    
      n
      =
      
        4
        *
        1024
      
    
    
      12
      *
      1024
    
  
  ⁢
  
    n
    ⨯
    
      (
      
        
          P
          ⁡
          
            (
            
              n
              -
              1
            
            )
          
        
        -
        
          P
          ⁡
          
            (
            n
            )
          
        
      
      )
    
  




may be performed according to the density function of a data stream dividing point, so as to obtain an expected length of a data stream dividing point, that is, the size of the average chunk, where 4*1024 (bytes) represents a length of the minimum data chunk, and 12*1024 (bytes) represents a length of the maximum data chunk.

On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 5, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 points px, a window Wx[px−Ax, px+Bx] (window W for short) corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. A distance between the point px and the potential dividing point k is dx bytes. Specifically, a distance between a point p1 and the potential dividing point k is 0 byte, a distance between a point p2 and the potential dividing point k 1 byte, a distance between a point p3 and the potential dividing point k is 2 bytes, a distance between a point p4 and the potential dividing point k is 3 bytes, a distance between a point pi5 and the potential dividing point k is 4 bytes, a distance between a point pi6 and the potential dividing point k is 5 bytes, a distance between a point p7 and the potential dividing point k is 6 bytes, a distance between a point p8 and the potential dividing point k is 7 bytes, a distance between a point p9 and the potential dividing point k is 8 bytes, a distance between a point p10 and the potential dividing point k is 9 bytes, a distance between a point p11 and the potential dividing point k is 10 bytes, and relative to the potential dividing point k, all the points p2, p3, p4, p5, p6, p7, p8, p9, p10, and p11 are in a direction opposite to a direction of searching for a data stream dividing point. ka is a data stream dividing point, and the direction of searching for a data stream dividing point shown in FIG. 5 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki, and a point pix is determined for the potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 5, 11 points are determined for the potential dividing point ki, and are pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 separately, and windows corresponding to the points pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11, are Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11] respectively. The foregoing windows are separately referred to as Wi1, Wi2, Wi3, Wi4, Wi5, Wi6, Wi7, Wi8, Wi9, Wi10, and Wi11, for short. A distance between the point pix and the potential dividing point ki is dx bytes. Specifically, a distance between pi1 and ki is 0 byte, a distance between pi2 and ki is 1 byte, a distance between pi3 and ki is 2 bytes, a distance between pi4 and ki is 3 bytes, a distance between pi5, and ki is 4 bytes, a distance between pi6 and ki is 5 bytes, a distance between pi7 and ki is 6 bytes, a distance between pi8 and ki is 7 bytes, a distance between pi9 and ki is 8 bytes, a distance between pi10 and ki is 9 bytes, a distance between pi11 and ki is 10 bytes, and relative to the potential dividing point ki, all pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1, it is determined whether at least a part of data in Wi2[pi2−169, pi2] meets a preset condition C2, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, for example, as shown in FIG. 6, at least a part of data in Wi5[pi5−169, pi5] does not meet the corresponding preset condition C5, N bytes are skipped from the point pi5 along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B5∥+maxx(∥Ax∥+∥(ki−pix)∥). In an implementation manner shown in FIG. 6, the N bytes that are skipped are not greater than 179 bytes, and in this embodiment, N=11, so as to obtain a next potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. According to the rule preset on the deduplication server 103 in the implementation manner shown in FIG. 5, 11 points are determined for the potential dividing point kj, and are pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 separately, and windows corresponding to the points pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are determined, and are Wj1[pj1−169, pj1], Wj2[pj2−169, pj2], Wj3[pj3−169, pj3], Wj4[pj4−169, pj4], Wj5[pj5−169, pj5], Wj6[pj6−169, pj6], Wj7[pj7−169, pj7], Wj8[pj8−169, pj8], Wj9[pj9−169, pj9], Wj10[pj10−169, pj10], and Wj11[pj11−169, pj11] respectively. A distance between pjx and the potential dividing point kj is dx bytes. Specifically, a distance between pj1 and kj is 0 byte, a distance between pj2 and kj is 1 byte, a distance between pj3 and kj is 2 bytes, a distance between pj4 and kj is 3 bytes, a distance between pj5 and kj is 4 bytes, a distance between pj6 and kj is 5 bytes, a distance between pj7 and kj is 6 bytes, a distance between pj8 and kj is 7 bytes, a distance between pj9 and kj is 8 bytes, a distance between pj10 and kj is 9 bytes, a distance between pj11 and kj is 10 bytes, and relative to the potential dividing point kj, all pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are in a direction opposite to the direction of searching for a data stream dividing point. In the implementation manner shown in FIG. 6, when the 11th window Wj11[pj11−169, pj11] is determined for the potential dividing point kj, to ensure that a range between the potential dividing point ki and the potential dividing point kj all fall within a determining range, in this implementation manner, it may be ensured that a left boundary of the window Wj11[pj11−169, pj11] coincides with a right boundary pi5, of Wi5[pi5−169, pi5,] or falls within a range of Wi5[pi5−169, pi5], where the point pj11 determined for the potential dividing point kj is a point ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M points that are determined for the potential dividing point kj according to the rule. Therefore, within such a limit, when the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, a distance for skipping from pi5, along the direction of searching for a data stream dividing point is not greater than ∥B5∥+maxx(∥Ax∥+∥(ki−pix)∥), where M=11, and 11*U is not greater than maxx∥Ax∥+∥(ki−pix)∥), and therefore, a distance for skipping from pi5, along the direction of searching for a data stream dividing point is not greater than 179. It is determined whether at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1, it is determined whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, it is determined whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103, whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, 11 bytes are skipped in a manner the same as that of ki to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
In the implementation manner shown in FIG. 5, according to the rule preset on the deduplication server 103, starting from determining whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1, when it is determined that the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1, it is determined that the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2, it is determined that the at least a part of data in Wi3[pi3−169, pi3] meets the preset condition C3, it is determined that the at least a part of data in Wi4[pi4−169, pi4] meets the preset condition C4, and it is determined that the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, 10 bytes are skipped from the point pi5, along the direction of searching for a data stream dividing point, and a new potential dividing point is obtained at an end position of a 10th byte, which is represented as kg here for differentiation from other potential dividing points. According to the rule preset on the deduplication server 103, 11 points pgx are determined for the potential dividing point kg, where x indicates consecutive natural numbers from 1 to 11 separately, and are pg1, pg2, pg3, pg4, pg5, pg6, pg7, pg8, pg9, pg10, and pg11 separately, and windows corresponding to the points pg1, pg2, pg3, pg4, pg5, pg6, pg7, pg8, pg9, pg10, and pg11 are determined, and are Wg1[pg1−169, pg1], Wg2[pg2−169, pg2], Wg3[pg3−169, pg3], Wg4[pg4−169, pg4], Wg5[pg5−169, pg5], Wg6[pg6−169, pg6], Wg7[pg7−169, pg7], Wg8[pg8−169, pg8], Wg9[pg9−169, pg9], Wg10[pg10−169, pg10], and Wg11[pg11−169, pg11] respectively. A distance between pgx and the potential dividing point kg is dx bytes. Specifically, a distance between pg1 and kg is 0 byte, a distance between pg2 and kg is 1 byte, a distance between pg3 and kg is 2 bytes, a distance between pg4 and kg is 3 bytes, a distance between pg5 and kg is 4 bytes, a distance between pg6 and kg is 5 bytes, a distance between pg7 and kg is 6 bytes, a distance between pg8 and kg is 7 bytes, a distance between pg9 and kg is 8 bytes, a distance between pg10 and kg is 9 bytes, a distance between pg11 and kg is 10 bytes, and relative to the potential dividing point kg, all pg2, pg3, pg4, pg5, pg6, pg7, pg8, pg9, pg10, and pg11 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wg1[pg1−169, pg1] meets the preset condition C1, it is determined whether at least a part of data in Wg2[pg2−169, pg2] meets the preset condition C2, it is determined whether at least a part of data in Wg3[pg3−169, pg3] meets the preset condition C3, it is determined whether at least a part of data in Wg4[pg4−169, pg4] meets the preset condition C4, it is determined whether at least a part of data in Wg5[pg5−169, pg5] meets the preset condition C5, it is determined whether at least a part of data in Wg6[pg6−169, pg6] meets the preset condition C6, it is determined whether at least a part of data in Wg7[pg7−169, pg7] meets the preset condition C7, it is determined whether at least a part of data in Wg8[pg8−169, pg8] meets the preset condition C8, it is determined whether at least a part of data in Wg9[pg9−169, pg9] meets the preset condition C9, it is determined whether at least a part of data in Wg10[pg10−169, pg10] meets the preset condition C10, and it is determined whether at least a part of data in Wg11[pg11−169, pg11] meets the preset condition C11. Therefore, the point pg11 corresponding to the potential dividing point kg coincides with the point pi5 corresponding to the potential dividing point ki, the window Wg11 [pg11−169, pg11] corresponding to the point pg11 coincides with the window Wi5[pi5−169, pi5] corresponding to the point pi5, and C5=C11; therefore, for the potential dividing point ki, when it is determined that the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, the potential dividing point kg obtained by skipping 10 bytes from the point pi5, along the direction of searching for a data stream dividing point still does not meet a condition of serving as a data stream dividing point. Therefore, if repeated calculation exists when 10 bytes are skipped from the point pi5 along the direction of searching for a data stream dividing point, then repeated calculation can be reduced and efficiency is higher when 11 bytes are skipped from the point pi5 along the direction of searching for a data stream dividing point. Therefore, a speed of searching for a data stream dividing point is increased. When a probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px that is determined according to the preset rule meets the preset condition Cx is 1⁄2, that is, a probability of executing skipping is 1⁄2, at most 179 bytes can be skipped each time.
In this implementation manner, a preset rule is: for a potential dividing point k, determining 11 points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to 11 separately, where a probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets the preset condition is 1⁄2, and P(n) can be calculated by using the two factors, that is, the quantity of points px and the probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets the preset condition. Moreover, A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11, where a distance between px and the potential dividing point k is dx bytes. Specifically, a distance between p1 and the potential dividing point k is 0 byte, a distance between p2 and k is 1 byte, a distance between p3 and k is 2 bytes, a distance between p4 and k is 3 bytes, a distance between p5 and k is 4 bytes, a distance between p6 and k is 5 bytes, a distance between p7 and k is 6 bytes, a distance between p8 and k is 7 bytes, a distance between p9 and k is 8 bytes, a distance between p10 and k is 9 bytes, a distance between p11 and k is 10 bytes, and relative to the potential dividing point k, all p2, p3, p4, p5, p6, p7, p8, p9, p10, and p11 are in a direction opposite to the direction of searching for a data stream dividing point. Therefore, whether the potential dividing point k is a data stream dividing point depends on whether it exists that at least a part of data in each window of windows corresponding to the 11 consecutive points meets the preset condition Cx. After a minimum chunk length of 4096 bytes is skipped from a start position/previous data stream dividing point of a data stream, a 4086th point is found by going back by 10 bytes in a direction opposite to the direction of searching for a data stream dividing point, and no data stream dividing point exists at the point; therefore, P(4086)=1, and P(4087)=1, . . . , P(4095)=1, and so on. At an 4096th point, that is, a point which is used to obtain the minimum chunk, with a probability of (1⁄2)^11, at least a part of data in each window of the windows corresponding to the 11 points meets the preset condition Cx. Hence, with a probability of (1⁄2)^11, a data stream dividing point exists; with a probability of 1−(1⁄2)^11, no data stream dividing point exists; therefore P(11)=1−(1⁄2)^11.
As shown in FIG. 34, at an nth point, there may be 12 cases of obtaining P(n) by means of recursion.
Case 1: With a probability of 1⁄2, at least a part of data in a window corresponding to the nth point does not meet a preset condition; in this case, with a probability of P(n−1), 11 consecutive points do not exist among (n−1) points before the nth point, where at least a part of data in each window of windows corresponding to the 11 consecutive points separately meets a preset condition. Therefore, P(n) includes 1⁄2*P(n−1). A case in which the at least a part of data in the window corresponding to the nth point does not meet the preset condition, and 11 consecutive points exist among the (n−1) points before the nth point, where at least a part of data in each window of windows corresponding to the 11 consecutive points separately meets the preset condition, is not related to P(n).
Case 2: With a probability of 1⁄2, at least a part of data in a window corresponding to the nth point meets a preset condition, and with the probability of 1⁄2, at least a part of data in a window corresponding to an (n−1)th point does not meet a preset condition; in this case, with a probability of P(n−2), 11 consecutive points do not exist among (n−2) points before the (n−1) point, where at least a part of data in each window of windows corresponding to 11 consecutive points separately meets a preset condition. Therefore, P(n) includes 1⁄2*1⁄2*P(n−2). A case in which the at least a part of data in the window corresponding to the nth point meets the preset condition, the at least a part of data in the window corresponding to the (n−1)th point does not meet the preset condition, and 11 consecutive points exist among the (n−2) points before the (n−1)th point, where at least a part of data in each window of windows corresponding to the 11 consecutive points separately meets the preset condition, is not related to P(n).
According to the foregoing description, case 11: With a probability of (1⁄2)^10, at least a part of data in windows corresponding to nth to (n−9)th points meets a preset condition, and with a probability of 1⁄2, at least a part of data in a window corresponding to an (n−10)th point does not meet a preset condition; in this case, with a probability of P(n−11), 11 consecutive points do not exist among (n−11) points before the (n−10) point, where at least a part of data in each window of windows corresponding to the 11 consecutive points separately meets a preset condition. Therefore, P(n) includes (1⁄2)^10*1⁄2*P(n−11). A case in which the at least a part of data in the windows corresponding to the nth to (n−9)th points meets the preset condition, the at least a part of data in the window corresponding to the (n−10)th point does not meet the preset condition, and 11 consecutive points exist among the (n−11) points before the (n−10)th point, where at least a part of data in each window of windows corresponding to the 11 consecutive points separately meets the preset condition, is not related to P(n).
Case 12: With a probability of (1⁄2)^11, at least a part of data in windows corresponding to nth to (n−10)th points meets a preset condition, and this case is not related to P(n).
Therefore, P(n)=1⁄2*P(n−1)+(1⁄2)^2*P(n−2)+ . . . +(1⁄2)^11*P(n−11). Another preset rule is: for a potential dividing point k, determining 24 points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to 24 separately, where a probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets the preset condition Cx is 3⁄4, and P(n) can be calculated by using the two factors, that is, the quantity of points px and the probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px, meets the preset condition. Moreover, A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9= . . . =C22=C23=C24, where a distance between px and the potential dividing point k is dx bytes. Specifically, a distance between p1 and the potential dividing point k is 0 byte, a distance between p2 and k is 1 byte, a distance between p3 and k is 2 bytes, a distance between p4 and k is 3 bytes, a distance between p5 and k is 4 bytes, a distance between p6 and k is 5 bytes, a distance between p7 and k is 6 bytes, a distance between p8 and k is 7 bytes, a distance between p9 and k is 8 bytes, . . . , a distance between p22 and k is 21 bytes, a distance between p23 and k is 22 bytes, a distance between p24 and k is 23 bytes, and relative to the potential dividing point k, all p2, p3, p4, p5, p6, p7, p8, p9, . . . , pi2, p23, and p24 are in a direction opposite to the direction of searching for a data stream dividing point. Therefore, whether the potential dividing point k is a data stream dividing point depends on whether it exists that at least a part of data in each window of windows corresponding to the 24 consecutive points meets the preset condition Cx, and calculation can be performed by using the following formulas:

P(4073)=1,P(4074)=1, . . . ,P(4095)=1,P(4096)=1−(3⁄4)^24, and

P(n)=1⁄4*P(n−1)+1⁄4*(3⁄4)*P(n−2)+ . . . +1⁄4*(3⁄4)^23*P(n−24).

After calculation, P(5*1024)=0.78, P(11*1024)=0.17, and P(12*1024)=0.13. That is, if no data stream dividing point is found with a probability of 13% after a search proceeds to a point at a distance of 12 KB from a start position/previous data stream dividing point of a data stream, and forced division is performed. A density function of a data stream dividing point is obtained by using this probability, and after integration, it is obtained that on average, a data stream dividing point is found after a search proceeds to a point at a distance about 7.6 KB from the start position/previous data stream dividing point of the data stream, that is, an average chunk length is about 7.6 KB. Different from that at least a part of data in windows corresponding to 11 consecutive points meets a preset condition with a probability of 1⁄2, a conventional CDC algorithm can achieve an effect of an average chunk length being 7.6 KB only when one window meets a condition with a probability of 1⁄2^12.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 7, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx [px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to 11 separately, where a probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets the preset condition Cx is 1⁄2, A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11, where a distance between px and the potential dividing point k is dx bytes. Specifically, a distance between p1 and the potential dividing point k is 2 bytes, a distance between p2 and k is 3 bytes, a distance between p3 and k is 4 bytes, a distance between p4 and k is 5 bytes, a distance between pi5 and k is 6 bytes, a distance between p6 and k is 7 bytes, a distance between p7 and k is 8 bytes, a distance between p8 and k is 9 bytes, a distance between p9 and k is 10 bytes, a distance between p10 and k is 1 byte, a distance between p11 and k is 0 byte, and relative to the potential dividing point k, all p1, p2, p3, p4, p5, p6, p7, p8, p9, and p10 are in a direction opposite to a direction of searching for a data stream dividing point. ka is a data stream dividing point, and the direction of searching for a data stream dividing point shown in FIG. 7 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki, and a point pix is determined for the potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 7, according to the preset rule, 11 points are determined for the potential dividing point ki, and are pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 separately, and windows corresponding to the points pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 are Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6,], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11] respectively. A distance between the point pix and the potential dividing point ki is dix bytes. Specifically, a distance between pi1 and ki is 2 bytes, a distance between pi2 and ki is 3 bytes, a distance between pi3 and ki is 4 bytes, a distance between pi4 and ki is 5 bytes, a distance between pi5 and ki is 6 bytes, a distance between pi6 and ki is 7 bytes, a distance between pi7 and ki is 8 bytes, a distance between pi8 and ki is 9 bytes, a distance between pi9 and ki is 10 bytes, a distance between pi10 and ki is 1 byte, a distance between pi11 and ki is 0 byte, and relative to the potential dividing point ki, all pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, and pi10 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1, it is determined whether at least a part of data in Wi2[pi2−169, pi2] meets a preset condition C2, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, as shown in FIG. 8, that the at least a part of data in Wi3[pi3−169, pi3] does not meet the preset condition C3 and 11 bytes are skipped from the point pi3 along a direction of searching for a data stream dividing point is used as an example for description. As shown in FIG. 8, when it is determined that W3 does not meet a preset condition, from p3 that serves as a start point, N bytes are skipped along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B3∥+maxx(∥Ax∥+∥(ki−pix)∥). In the implementation manner shown in FIG. 6, N bytes are skipped, and specifically are not greater than 179 bytes, and in this embodiment, N=11. A next potential dividing point is obtained at an end position of an 11th byte. For differentiation from the potential dividing point ki, the new potential dividing point is represented as ki here. According to the rule preset on the deduplication server 103, 11 points are determined for the potential dividing point kj, and are pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 separately, and windows corresponding to the points pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are determined, and are Wj1[pj1−169, pj1], Wj2[pj2−169, pj2], Wj3[pj3−169, pj3], Wj4[pj4−169, pj4], Wj5[pj5−169, pj5], Wj6[pj6−169, pj6], Wj7[pj7−169, pj7], Wj8[pj8−169, pj8], Wj9[pj9−169, pj9], Wj10[pj10−169, pj10], and Wj11[pj11−169, pj11] respectively. A distance between pjx and the potential dividing point kj is dx bytes. Specifically, a distance between pj1 and kj is 2 bytes, a distance between pj2 and kj is 3 bytes, a distance between pj3 and kj is 4 bytes, a distance between pj4 and kj is 5 bytes, a distance between pj5 and kj is 6 bytes, a distance between pj6 and kj is 7 bytes, a distance between pj7 and kj is 8 bytes, a distance between pj8 and kj is 9 bytes, a distance between pj9 and kj is 10 bytes, a distance between pj10 and kj is 1 byte, a distance between pj11, and kj is 0 byte, and relative to the potential dividing point kj, all pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, and pj10 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1, it is determined whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, it is determined whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103, whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, 11 bytes are skipped in a manner the same as that of ki to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point. Certainly, implementation of the method is restricted by a length of the maximum data chunk and a size of a file forming the data stream, which is not described herein again.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 9, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 points px, a window Wx[px−Ax, p+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B9=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. A distance between px and the potential dividing point k is dx bytes. Specifically, a distance between p1 and the potential dividing point k is 3 bytes, a distance between p2 and k is 2 bytes, a distance between p3 and k is 1 byte, a distance between p4 and k is 0 byte, a distance between p5 and k is 1 byte, a distance between p6 and k is 2 bytes, a distance between p7 and k is 3 bytes, a distance between p8 and k is 4 bytes, a distance between p9 and k is 5 bytes, a distance between p10 and k is 6 bytes, a distance between p11 and k is 7 bytes, all p5, p6, p7, p8, p9, p10, and p11 are, relative to the potential dividing point k, in a direction opposite to a direction of searching for a data stream dividing point, and all p1, p2, and p3 are, relative to the potential dividing point k, in the direction of searching for a data stream dividing point. ka is a data stream dividing point, and the direction of searching for a data stream dividing point shown in FIG. 9 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki, and a point pix is determined for the potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 9, 11 points are determined for a potential dividing point ki, and are pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 separately, and windows corresponding to the points pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 are Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11] respectively. A distance between pix and the potential dividing point ki is dx bytes. Specifically, a distance between pi1 and ki is 3 bytes, a distance between pi2 and ki is 2 bytes, a distance between pi3 and ki is 1 byte, a distance between pi4 and ki is 0 byte, a distance between pi5 and ki is 1 byte, a distance between pi6 and ki is 2 bytes, a distance between pi7 and ki is 3 bytes, a distance between pi8 and ki is 4 bytes, a distance between pi9 and ki is 5 bytes, a distance between pi10 and ki is 6 bytes, a distance between pi11 and ki is 7 bytes, all pi5, pi6, pi7, pi8, pi9, pi10, and pi11 are, relative to the potential dividing point ki, in a direction opposite to the direction of searching for a data stream dividing point, and all pi1, pi2, and pi3 are, relative to the potential dividing point ki, in the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1, it is determined whether at least a part of data in Wi2[pi2−169, pi2] meets a preset condition C2, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5, meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, for example, as shown in FIG. 10, at least a part of data in Wi7[pi7−169, pi7] does not meet a corresponding preset condition, N bytes are skipped from the point pi7 along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B4∥+maxx(∥Ax∥+∥(ki−pix)∥). In an implementation manner shown in FIG. 10, N bytes that are skipped are specifically not greater than 179 bytes, and in this embodiment, specifically, N=8, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. According to the rule preset on the deduplication server 103 in the implementation manner shown in FIG. 9, 11 points are determined for the potential dividing point ki, and are pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 separately, and windows corresponding to the points pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are determined, and are Wj1[pj1−169, pj1], Wj2[pj2−169, pj2], Wj3[pj3−169, pj3], Wj4[pj4−169, pj4], Wj5[pj5−169, pj5], Wj6[pj6−169, pj6], Wj7[pj7−169, pj7], Wj8[pj8−169, pj8], Wj9[pj9−169, pj9], Wj10[pj10−169, pj10], and Wj11[pj11−169, pj11] respectively. A distance between pjx and the potential dividing point kj is dx bytes. Specifically, a distance between pj1 and kj is 3 bytes, a distance between pj2 and kj is 2 bytes, a distance between pj3 and kj is 1 byte, a distance between pj4 and kj is 0 byte, a distance between pj5 and kj is 1 byte, a distance between pj6 and kj is 2 bytes, a distance between pj7 and kj is 3 bytes, a distance between pj8 and kj is 4 bytes, a distance between pj9 and kj is 5 bytes, a distance between pj10 and kj is 6 bytes, a distance between pj11 and kj is 7 bytes, all pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are, relative to the potential dividing point kj, in a direction opposite to the direction of searching for a data stream dividing point, and all pj1, pj2, and pj3 are, relative to the potential dividing point kj, in the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1, it is determined whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, it is determined whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103, whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, 8 bytes are skipped in a manner the same as that of ki to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 11, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx [px−Ax, px+Bx], where A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=169, A11=182, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6C7=C8=C9=C10≠C11. A distance between px and the potential dividing point k is dx bytes. Specifically, a distance between p1 and the potential dividing point k is 0 byte, a distance between p2 and k is 1 byte, a distance between p3 and k is 2 bytes, a distance between p4 and k is 3 bytes, a distance between p5 and k is 4 bytes, a distance between p6 and k is 5 bytes, a distance between p7 and k is 6 bytes, a distance between p8 and k is 7 bytes, a distance between p9 and k is 8 bytes, a distance between p10 and k is 1 byte, a distance between p11 and k is 3 bytes, all p2, p3, p4, p5, p6, p7, p8, and p9 are, relative to the potential dividing point k, in a direction opposite to a direction of searching for a data stream dividing point, and both p10 and p11 are, relative to the potential dividing point k, in the direction of searching for a data stream dividing point. ka is a data stream dividing point, and the direction of searching for a data stream dividing point shown in FIG. 11 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki, and a point pix is determined for the potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 11, 11 points are determined for the potential dividing point ki, and are pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 separately, and windows corresponding to the points pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11, are Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−182, pi11] respectively. A distance between pix and the potential dividing point ki is dx bytes. Specifically, a distance between pi1 and ki is 0 byte, a distance between pi2 and ki is 1 byte, a distance between pi3 and ki is 2 bytes, a distance between pi4 and ki is 3 bytes, a distance between pi5 and ki is 4 bytes, a distance between pi6 and ki is 5 bytes, a distance between pi7 and ki is 6 bytes, a distance between pi8 and ki is 7 bytes, a distance between pi9 and ki is 8 bytes, a distance between pi10 and ki is 1 byte, a distance between pi11 and ki is 3 bytes, all pi2, pi3, pi4, pi5, pi6, pi7, pi8, and pi9 are relative to the potential dividing point ki, in a direction opposite to the direction of searching for a data stream dividing point, and both pi10 and pi11 are, relative to the potential dividing point ki, in the direction of searching for a data stream dividing point. It is determined whether at least a part of data in the Wi1[pi1−169, pi1] meets a preset condition C1, it is determined whether at least a part of data in the Wi2[pi2−169, pi2] meets a preset condition C2, it is determined whether at least a part of data in the Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in the Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in the Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in the Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in the Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in the Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in the Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in the Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in the Wi11[pi11−169, pi11] meets a preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2, meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When it is determined that the at least a part of data in the window Wi11 does not meet the preset condition C11, 1 byte is skipped from the potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. When the at least a part of data in any window of the 10 windows Wi1, Wi2, Wi3, Wi4, Wi5, Wi6, Wi7, Wi8, Wi9, and Wi10 does not meet the corresponding preset condition, for example, Wi4[pi4−169, pi4] shown in FIG. 12, N bytes are skipped from the point pi4 along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B4∥+maxx(∥Ax∥+∥(ki−pix)∥). In an implementation manner shown in FIG. 12, the N bytes that are skipped are specifically not greater than 179, and in this embodiment, specifically, N=9, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. According to the rule preset on the deduplication server 103 in the implementation manner shown in FIG. 11, 11 points are determined for the potential dividing point kj, and are pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 separately, and windows corresponding to the points pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, p10, and pj11 are determined, and are Wj1[pj1−169, pj1], Wj2[pj2−169, pj2], Wj3[pj3−169, pj3], Wj4[pj4−169, pj4], Wj5[pj5−169, pj5], Wj6[pj6−169, pj6], Wj7[pj7−169, pj7], Wj8[pj8−169, pj8], Wj9[pj9−169, pj9], Wj10[pj10−169, pj10], and Wj11[pj8−182, pj8] respectively. A distance between pjx and the potential dividing point kj is dx bytes. Specifically, a distance between pj1 and kj is 0 byte, a distance between pj2 and kj is 1 byte, a distance between pj3 and kj is 2 bytes, a distance between pj4 and kj is 3 bytes, a distance between pj5 and kj is 4 bytes, a distance between pj6 and kj is 5 bytes, a distance between pj7 and kj is 6 bytes, a distance between pj8 and kj is 7 bytes, a distance between pj9 and kj is 8 bytes, a distance between Pj10 and kj is 1 byte, a distance between pj11 and kj is 3 bytes, all pj2, pj3, pj4, pj5, pj6, Pj7, pj8, and pj9 are, relative to the potential dividing point kj, in a direction opposite to the direction of searching for a data stream dividing point, and both pj10 and pj11 are, relative to the potential dividing point kj, in the direction of searching for a data stream dividing point. It is determined whether at least a part of data in the Wj1[pj1−169, pj1] meets the preset condition C1, it is determined whether at least a part of data in the Wj2[pj2−169, pj2] meets the preset condition C2, it is determined whether at least a part of data in the Wj3[pj3−169, pj3] meets the preset condition C3, it is determined whether at least a part of data in the Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in the Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in the Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in the Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in the Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in the Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in the Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in the Wj11[pj11−182, pj11] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and it is determined, according to the rule preset on the deduplication server 103, whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, a next potential dividing point is obtained in a manner the same as that of ki, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 13, a rule that is preset on a deduplication server 103 is: for a potential dividing point k, determining 11 points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to 11 separately, where a probability that at least a part of data in the window Wx[px−Ax, px+Bx] corresponding to the point px meets a preset condition is 1⁄2, A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11, where a distance between px and the potential dividing point k is dx bytes. Specifically, a distance between p1 and the potential dividing point k is 0 byte, a distance between p2 and k is 2 bytes, a distance between p3 and k is 4 bytes, a distance between p4 and k is 6 bytes, a distance between p5 and k is 8 bytes, a distance between p6 and k is 10 bytes, a distance between p7 and k is 12 bytes, a distance between p8 and k is 14 bytes, a distance between p9 and k is 16 bytes, a distance between p10 and k is 18 bytes, a distance between p11 and k is 20 bytes, and relative to the potential dividing point k, all p2, p3, p4, p5, p6, p7, p8, p9, p10, and p11 are in a direction opposite to a direction of searching for a data stream dividing point. ka is a data stream dividing point, and the direction of searching for a data stream dividing point shown in FIG. 13 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki, and a point pix is determined for the potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 13, according to the preset rule, 11 points are determined for the potential dividing point ki, and are pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 separately, and windows corresponding to the points pi1, pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 are Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11] respectively. A distance between pix and the potential dividing point ki is dx bytes. Specifically, a distance between pi1 and ki is 0 byte, a distance between pi2 and ki is 2 bytes, a distance between pi3 and ki is 4 bytes, a distance between pi4 and ki is 6 bytes, a distance between pi5 and ki is 8 bytes, a distance between pi6 and ki is 10 bytes, a distance between pi7, and ki is 12 bytes, a distance between pi8 and ki is 14 bytes, a distance between pi9 and ki is 16 bytes, a distance between pi10 and ki is 18 bytes, a distance between pi11 and ki is 20 bytes, and relative to the potential dividing point ki, all pi2, pi3, pi4, pi5, pi6, pi7, pi8, pi9, pi10, and pi11 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1, it is determined whether at least a part of data in Wi2[pi2−169, pi2] meets a preset condition C2, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, for example, as shown in FIG. 14, the at least a part of data in Wi4 [pi4−169, pi4] does not meet the preset condition C4, a next potential dividing point is selected. For differentiation from the potential dividing point ki, the next potential dividing point is represented as kj here, where kj is located on the right of ki, and a distance between kj and ki is 1 byte. As shown in FIG. 14, according to the rule preset on the deduplication server 103, 11 points are determined for the potential dividing point kj, and are pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 separately, and windows corresponding to the points pj1, pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are determined, and are Wj1[pj1−169, pj1], Wj2[pj2−169, pj2], Wj3[pj3−169, pj3], Wj4[pj4−169, pj4], Wj5[pj5−169, pj5], Wj6[pj6−169, pj6], Wj7[pj7−169, pj7], Wj8[pj8−169, pj8], Wj9[pj9−169, pj9], Wj10[pj10−169, pj10], and Wj11[pj11−169, pj11] respectively, where A1=A2=A3=A4=A5=A6=A7=A8=A9=A10=A11=169, B1=B2=B3=B4=B5=B6=B7=B8=B9=B10=B11=0, and C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. A distance between pjx and the potential dividing point kj is dx bytes. Specifically, a distance between pj1 and kj is 0 byte, a distance between pj2 and kj is 2 bytes, a distance between pj3 and kj is 4 bytes, a distance between pj4 and kj is 6 bytes, a distance between pj5 and kj is 8 bytes, a distance between pj6 and kj is 10 bytes, a distance between pj7 and kj is 12 bytes, a distance between pj8 and kj is 14 bytes, a distance between pj9 and kj is 16 bytes, a distance between pj10 and kj is 18 bytes, a distance between pj11 and kj is 20 bytes, and relative to the potential dividing point kj, all pj2, pj3, pj4, pj5, pj6, pj7, pj8, pj9, pj10, and pj11 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1, it is determined whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, it is determined whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point. When it is determined that the at least a part of data in any window of the windows Wj1 Wj2, Wj3, Wj4, Wj5, Wj6, Wj7, Wj8, Wj9, Wj10, and Wj11 does not meet the preset condition, for example, as shown in FIG. 15, when the at least a part of data in Wj3[pj3−169, pj3] does not meet the preset condition C3, the point pi4 is located on the left of the point pj3 relative to the direction of searching for a data stream dividing point, and 21 bytes are skipped from the point pi4 along the direction of searching for a data stream dividing point, so as to obtain a next potential dividing point. For differentiation from the potential dividing points ki and kj, the next potential dividing point is represented as ki. According to the rule preset on the deduplication server 103 in the implementation manner shown in FIG. 13, 11 points are determined for the potential dividing point kl, and are pl1, pl2, pl3, pl4, pl5, pl6, pl7, pl8, pl9, pl10, and pl11 separately, and windows corresponding to the points pl1, pl2, pl3, pl4, pl5, pl6, pl7, pl8, pl9, pl10, and pl11, are Wl1[pl1−169, pl1], Wl2[pl2−169, pl2], Wl3[pl3−169, pl3], Wl4[pl4−169, pl4], Wl5[pl5−169, pl5], Wl6[pl6−169, pl6], Wl7[pl7−169, pl7], Wl8[pl8−169, pl8], Wl9[pl9−169, pl9], Wl10[pl10−169, pl10], and Wl11[pl11−169, pl11] respectively, where a distance between plx and the potential dividing point kl is dx bytes. Specifically, a distance between pl1 and the potential dividing point kl is 0 byte, a distance between pl2 and kl is 2 bytes, a distance between pl3 and kl is 4 bytes, a distance between pl4 and kl is 6 bytes, a distance between pl5 and kl is 8 bytes, a distance between pl6 and kl is 10 bytes, a distance between pl7 and kl 12 bytes, a distance between pl8 and kl is 14 bytes, a distance between pl9 and kl is 16 bytes, a distance between pl10 and kl is 18 bytes, a distance between pl11 and kl is 20 bytes, and relative to the potential dividing point kl, all pl2, pl3, pl4, pl5, pl6, pl7, pl8, pl9, pl10, and pl11 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wl1[pl1−169, pl1] meets the preset condition C1, it is determined whether at least a part of data in Wl2[pl2−169, pl2] meets the preset condition C2, it is determined whether at least a part of data in Wl3[pl3−169, pl3] meets the preset condition C3, it is determined whether at least a part of data in Wl4[pl4−169, pl4] meets the preset condition C4, it is determined whether at least a part of data in Wl5[pl5−169, pl5] meets the preset condition C5, it is determined whether at least a part of data in Wl6[pl6−169, pl6] meets the preset condition C6, it is determined whether at least a part of data in Wl7[pl7−169, pl7] meets the preset condition C7, it is determined whether at least a part of data in Wl8[pl8−169, pl8] meets the preset condition C8, it is determined whether at least a part of data in Wl9[pl9−169, pl9] meets the preset condition C9, it is determined whether at least a part of data in Wl10[pl10−169, pl10] meets the preset condition C10, and it is determined whether at least a part of data in Wl11[pl11−169, pl11] meets the preset condition C11. When it is determined that the at least a part of data in the window Wl1 meets the preset condition C1, the at least a part of data in the window Wl2 meets the preset condition C2, the at least a part of data in the window Wl3 meets the preset condition C3, the at least a part of data in the window Wl4 meets the preset condition C4, the at least a part of data in the window Wl5 meets the preset condition C5, the at least a part of data in the window Wl6 meets the preset condition C6, the at least a part of data in the window Wl7 meets the preset condition C7, the at least a part of data in the window Wl8 meets the preset condition C8, the at least a part of data in the window Wl9 meets the preset condition C9, the at least a part of data in the window Wl10 meets the preset condition C10, and the at least a part of data in the window Wl11 meets the preset condition C11, the current potential dividing point kl is a data stream dividing point. When the at least a part of data in any window of the windows Wl1, Wl2, Wl3, Wl4, Wl5, Wl6, Wl7, Wl8, Wl9, Wl10, and Wl11 does not meet the preset condition, a next potential dividing point is selected. For differentiation from the potential dividing points ki, kj, and kl, the next potential dividing point is represented as km, where km is located on the right of kl, and a distance between km and kl is 1 byte. According to the rule preset on the deduplication server 103 in the embodiment shown in FIG. 13, 11 points are determined for the potential dividing point km, and are pm1, pm2, pm3, pm4, pm5, pm6, pm7, pm8, pm9, pm10, and pm11 separately, and windows corresponding to the points pm1, pm2, pm3, pm4, pm5, pm6, pm7, pm8, pm9, pm10, and pm11 are Wm1[pm1−169, pm1], Wm2[pm2−169, pm2], Wm3[pm3−169, pm3], Wm4[pm4−169, pm4], Wm5[pm5−169, pm5], Wm6[pm6−169, pm6], Wm7[pm7−169, pm7], Wm8[pm8−169, pm8], Wm9[pm9−169, pm9], Wm10[pm10−169, pm10], and Wm11[pm11−169, pm11] respectively, where a distance between pmx and the potential dividing point km is dx bytes. Specifically, a distance between pm1 and the potential dividing point km is 0 byte, a distance between pm2 and km is 2 bytes, a distance between pm3 and km is 4 bytes, a distance between pm4 and km is 6 bytes, a distance between pm5 and km is 8 bytes, a distance between pm6 and km is 10 bytes, a distance between pm7 and km is 12 bytes, a distance between pm8 and km 14 bytes, a distance between pm9 and km is 16 bytes, a distance between pm10 and km is 18 bytes, a distance between pm11 and km is 20 bytes, and relative to the potential dividing point km, all pm2, pm3, pm4, pm5, pm6, pm7, pm8, pm9, pm10, and pm11 are in a direction opposite to the direction of searching for a data stream dividing point. It is determined whether at least a part of data in Wm1[pm1−169, pm1] meets the preset condition C1, it is determined whether at least a part of data in Wm2[pm2−169, pm2] meets the preset condition C2, it is determined whether at least a part of data in Wm3[pm3−169, pm3] meets the preset condition C3, it is determined whether at least a part of data in Wm4[pm4−169, pm4] meets the preset condition C4, it is determined whether at least a part of data in Wm5 [pm5−169, pm5] meets the preset condition C5, it is determined whether at least a part of data in Wm6[pm6−169, pm6] meets the preset condition C6, it is determined whether at least a part of data in Wm7[pm7−169, pm7] meets the preset condition C7, it is determined whether at least a part of data in Wm8[pm8−169, pm8] meets the preset condition C8, it is determined whether at least a part of data in Wm9[pm9−169, pm9] meets the preset condition C9, it is determined whether at least a part of data in Wm10[pm10−169, pm10] meets the preset condition C10, and it is determined whether at least a part of data in Wm11[pm11−169, pm11] meets the preset condition C11. When it is determined that the at least a part of data in the window Wm1 meets the preset condition C1, the at least a part of data in the window Wm2 meets the preset condition C2, the at least a part of data in the window Wm3 meets the preset condition C3, the at least a part of data in the window Wm4 meets the preset condition C4, the at least a part of data in the window Wm5 meets the preset condition C5, the at least a part of data in the window Wm6 meets the preset condition C6, the at least a part of data in the window Wm7 meets the preset condition C7, the at least a part of data in the window Wm8 meets the preset condition C8, the at least a part of data in the window Wm9, meets the preset condition C9, the at least a part of data in the window Wm10 meets the preset condition C10, and the at least a part of data in the window Wm11 meets the preset condition C11, the current potential dividing point km is a data stream dividing point. When the at least a part of data in any window does not meet the preset condition, skipping is executed according to the solution described above, so as to obtain a next potential dividing point, and it is determine whether the next potential dividing point is a data stream dividing point.
An embodiment of the present invention provides a method for determining whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition Cz. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz, and the implementation manner shown in FIG. 5 is used as an example. According to a rule preset on a deduplication server 103, a point pi1 and a window Wi1[pi1−169, pi1] corresponding to the point pi1 are determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1. As shown in FIG. 16, Wi1 represents the window Wi1[pi1−169, pi1], and 5 bytes are selected to determine whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In FIG. 16, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              255
              ,
              1
            
          
        
        
          
            a
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




where when am,n=1, Vam,n=1, and when am,n=, Vam,n=−1, where am,n represents any one of am,1, . . . , and am,8, and a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
          
        
      
    
    )
  
  .




A large quantity of random numbers is selected to form a matrix, and once being formed, the matrix formed by the random numbers remains unchanged. For example, 255*8 random numbers are selected from random numbers that follow specific distribution (normal distribution is used as an example here) to form a matrix R:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




where random numbers of an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8. Sa1, Sa2, . . . , and Sa255 are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sa1, Sa2, . . . , and Sa255 is counted. Because the matrix R follows normal distribution, Sam still follows normal distribution as the matrix R does. According to a probability theory, a probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sa1, Sa2, . . . , and Sa255 is greater than 0 is 1⁄2, and therefore, K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sa1, Sa2, . . . , and Sa255 is an even number; a probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. When K is an odd number, it indicates that the at least a part of data in Wi1[pi1−169, pi1] does not meet the preset condition C1. C1 here refers to that the quantity K, which is obtained according to the foregoing manner, of values greater than 0 among Sa1, Sa2, . . . , and Sa255 is an even number. In the implementation manner shown in FIG. 5, for Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11], the windows are the same in size, that is, all the windows have a size of 169 bytes, and manners of determining whether at least a part of data in a window meets a preset condition are also the same. For details, refer to the foregoing description of determining whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 16, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi2[pi2−169, pi2] meets a preset condition C2, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as bm,1, . . . , and bm,8, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:





  
    (
    
      
        
          
            b
            
              1
              ,
              1
            
          
        
        
          
            b
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            b
            
              1
              ,
              8
            
          
        
      
      
        
          
            b
            
              2
              ,
              1
            
          
        
        
          
            b
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            b
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            b
            
              255
              ,
              1
            
          
        
        
          
            b
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            b
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




where when bm,n=1, Vbm,n=1, and when bm,n=0, Vbm,n=−1, where bm,n represents any one of bm,1, . . . , and bm,8, and a matrix Vb is obtained according to a conversion relationship between bm,n and Vbm,n from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
          
        
      
    
    )
  
  .




A manner of determining whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition is the same as a manner of determining whether at least a part of data in the window Wi2[pi2−169, pi2] meets a preset condition; therefore the matrix R is used:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




and random numbers of an mth row of the matrix Vb and the mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sbm=Vbm,1*hm,1+Vbm,2*hm,2+ . . . +Vbm,8*hm,8. Sb1, Sb2, . . . , and Sb255 are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sb1, Sb2, . . . , and Sb255 is counted. Because the matrix R follows normal distribution, Sbm still follows normal distribution as the matrix R does. According to the probability theory, the probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sb1, Sb2, . . . , and Sb255 is greater than 0 is 1⁄2, and therefore, K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sb1, Sb2, . . . , and Sb255 is an even number; the probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2. When K is an odd number, it indicates that the at least a part of data in Wi2[pi2−169, pi2] does not meet the preset condition C2. C2 here refers to that the quantity K, which is obtained according to the foregoing manner, of values greater than 0 among Sb1, Sb2, . . . , and Sb255 is an even number. In the implementation manner shown in FIG. 3, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2.

Therefore, as shown in FIG. 16, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi3[pi3−169, pi3] meets a preset condition C3, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Then, the method for determining whether at least a part of data in the windows Wi1[pi1−169, pi1] and Wi2[pi2−169, pi2] meets a preset condition is used to determine whether the at least a part of data in Wi3[pi3−169, pi3] meets the preset condition C3. In the implementation manner shown in FIG. 5, the at least a part of data in Wi3[pi3−169, pi3] meets the preset condition. As shown in FIG. 16, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi4[pi4−169, pi4] meets a preset condition C4, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Then, the method for determining whether at least a part of data in windows Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], and Wi3[pi3−169, pi3] meets a preset condition is used to determine whether the at least a part of data in Wi4[pi4−169, pi4] meets the preset condition C4. In the implementation manner shown in FIG. 5, the at least a part of data in Wi4 [pi4−169, pi4] meets the preset condition C4. As shown in FIG. 16, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi5[pi5−169, pi5] meets a preset condition C5, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Then, the method for determining whether at least a part of data in the windows Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], and Wi4[pi4−169, pi4] meets a preset condition is used to determine whether the at least a part of data in Wi5[pi5−169, pi5] meets the preset condition C5. In the implementation manner shown in FIG. 5, the at least a part of data in Wi5 [pi5−169, pi5] does not meet the preset condition C5.
When the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, 11 bytes are skipped from a point pi5, along a direction of searching for a data stream dividing point, and a next potential dividing point kj is obtained at an end position of an 11th byte. As shown in FIG. 6, according to the rule preset on the deduplication server 103, a point pj1 and a window Wj1[pj1−169, pj1] corresponding to the point pj1 are determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 17, Wj1 represents the window Wj1[pj1−169, pj1], and 5 bytes are selected to determine whether the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as am,1′, . . . , and am,8′, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
            ′
          
        
        
          
            a
            
              1
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
            ′
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
            ′
          
        
        
          
            a
            
              2
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
            ′
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              255
              ,
              1
            
            ′
          
        
        
          
            a
            
              255
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            a
            
              255
              ,
              8
            
            ′
          
        
      
    
    )
  
  ,




where when am,n′=1, Vam,n′=1, and when am,n′=0, Vam,n′=−1, where am,n′ represents any one of am,1′, . . . , and am,8′, and a matrix Va′ is obtained according to a conversion relationship between am,n′ and Vam,n′ from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
            ′
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
            ′
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
            ′
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
            ′
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
            ′
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
            ′
          
        
      
    
    )
  
  .




A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets a preset condition is the same as a manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets a preset condition. Therefore, the matrix R is used:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




and random numbers of an mth row of the matrix Va′ and the mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam′=Vam,1′*hm,1+Vam,2′*hm,2+ . . . +Va,8′*hm,8. Sa1′, Sa2′, . . . , and Sa255′ are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sa1′, Sa2′, . . . , and Sa255′ is counted. Because the matrix R follows normal distribution, Sam′ still follows normal distribution as the matrix R does. According to the probability theory, the probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sa1′, Sa2′, . . . , and Sa255′ is greater than 0 is 1⁄2, and therefore, K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sa1′, Sa2′, . . . , and Sa255′ is an even number; the probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. When K is an odd number, it indicates that the at least a part of data in Wj1[pj1−169, pj1] does not meet the preset condition C1.

A manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[pj2−169, pj2] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as bm,1′, . . . and bm,8′, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:




  
    (
    
      
        
          
            b
            
              1
              ,
              1
            
            ′
          
        
        
          
            b
            
              1
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            b
            
              1
              ,
              8
            
            ′
          
        
      
      
        
          
            b
            
              2
              ,
              1
            
            ′
          
        
        
          
            b
            
              2
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            b
            
              2
              ,
              8
            
            ′
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            b
            
              255
              ,
              1
            
            ′
          
        
        
          
            b
            
              255
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            b
            
              255
              ,
              8
            
            ′
          
        
      
    
    )
  
  ,




where when bm,n′=1, Vbm,n′=1, and when bm,n′=0, Vbm,n′=−1, where bm,n′ represents any one of bm,1′, . . . , and bm,8′, and a matrix Vb′ is obtained according to a conversion relationship between bm,n′ and Vbm,n′ from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
          
        
      
    
    )
  
  .




Manners of determining whether at least a part of data in windows W2[p2−169, p2] and W2[q2−169, q2] meets a preset condition are the same, and therefore the matrix R is still used:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  .




Random numbers of an mth row of the matrix Vb′ and the mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sbm′=Vbm,1′*hm,1+Vbm,2′*hm,2+ . . . +Vbm,8′*hm,8. Sb1′, Sb2′, . . . , and Sb255′ are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sb1′, Sb2′, . . . , and Sb255′ is counted. Because the matrix R follows normal distribution, Sbm′ still follows normal distribution as the matrix R does. According to the probability theory, the probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sb1′, Sb2′, . . . , and Sb255′ is greater than 0 is 1⁄2, and therefore, K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sb1′, Sb2′, . . . , and Sb255′ is an even number; the probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. When K is an odd number, it indicates that the at least a part of data in Wj2[pj2−169, pj2] does not meet the preset condition C2. Similarly, a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets a preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets a preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets a preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets a preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets a preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets a preset condition C11, which are not described herein again.

Still using the implementation manner shown in FIG. 5 as an example, a method for determining whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition Cz is provided. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. According to a rule preset on a deduplication server 103, a point pi1 and a window Wi1[pi1−169, pi1] corresponding to pi1 are determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1. As shown in FIG. 16, Wi1 represents the window Wi1[pi1−169, pi1], and 5 bytes are selected to determine whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In FIG. 16, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes “”. In one implementation manner, a hash function is used to calculate the 5 selected bytes, and values obtained by means of calculation by using the hash function are in fixed and even distribution. If a value obtained by means of calculation by using the hash function is an even number, it is determined that the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1, that is, C1 represents that a value obtained by means of calculation by using the hash function and according to the foregoing manner is an even number. Therefore, a probability that at least a part of data in Wi1[pi1−169, pi1] meets a preset condition is 1⁄2. In the implementation manner shown in FIG. 5, it is determined, by using a hash function, whether at least a part of data in Wi2[pi2−169, pi2] meets a preset condition C2, whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, and whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5. For specific implementation, reference may be made to the description of the manner of determining, by using a hash function, whether at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1 in the implementation manner shown in FIG. 5, which is not described herein again.
When the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, 11 bytes are skipped from a point pi5 along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of an 11th byte. As shown in FIG. 6, according to the rule preset on the deduplication server 103, a point pj1 and a window Wj1[pj1−169, pj1] corresponding to the point pj1 are determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 17, Wj1 represents the window Wj1[pj1−169, pj1], and 5 bytes are selected to determine whether the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes “”. The 5 bytes selected from the window Wj1[pj1−169, pj1] are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, a manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[pj2−169, pj2] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes “”. Selected 5 bytes are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. In FIG. 17, a manner of determining whether at least a part of data in Wi3 [pi3−169, pi3] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj3[pj3−169, pj3] meets the preset condition C3, and there are 42 bytes between two adjacent selected bytes “”. Selected 5 bytes are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. In FIG. 17, a manner of determining whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4 is the same as a manner of determining whether at least a part of data in the window Wi4[pi4−169, pi4] meets the preset condition C4. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj4[pj4−169, pj4] meets the preset condition C4, and there are 42 bytes between two adjacent selected bytes “”. Selected 5 bytes are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4. According to the foregoing method, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets a preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets a preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets a preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets a preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets a preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets a preset condition C11, which are not described herein again.
Using the implementation manner shown in FIG. 5 as an example, a method for determining whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition Cz is provided. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. According to a rule preset on a deduplication server 103, a point pi1 and a window Wi1[pi1−169, pi1] corresponding to pi1 are determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1. As shown in FIG. 16, Wi1 represents the window Wi1[pi1−169, pi1], and 5 bytes are selected to determine whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In FIG. 16, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1, a2, a3, a4, and a5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any ar of a1, a2, a3, a4, and a5 meets 0≦ar≦255. a1, a2, a3, a4, and a5 form a 1*5 matrix. 256*5 random numbers are selected from random numbers that follow binomial distribution to form a matrix R that is represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




The matrix R is searched for a corresponding value according to the value of a1 and a column in which a1 is located. For example, if a1=36, and a1 is located in a 1st column, a value corresponding to h36,1 is searched for. The matrix R is searched for a corresponding value according to the value of a2 and a column in which a2 is located. For example, if a2=48, and a, is located in a 2nd column, a value corresponding to h48,2 is searched for. The matrix R is searched for a corresponding value according to the value of a3 and a column in which a3 is located. For example, if a3=26, and a3 is located in a 3rd column, a value corresponding to h26,3 is searched for. The matrix R is searched for a corresponding value according to the value of a4 and a column in which a4 is located. For example, if a4=26, and a4 is located in a 4th column, a value corresponding to h26,4 is searched for. The matrix R is searched for a corresponding value according to the value of a5 and a column in which a5 is located. For example, if a5=88, and a5 is located in a 5th column, a value corresponding to h88,5 is searched for. S1=h36,1+h48,2+h26,3+h26,4+h88,5, and because the matrix R follows binomial distribution, S1 also follows binomial distribution. When S1 is an even number, the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1; when S1 is an odd number, the at least a part of data in Wi1[pi1−169, pi1] does not meet the preset condition C1. A probability that S1 is an even number is 1⁄2, and C1 represents that S1 that is obtained by means of calculation according to the foregoing manner is an even number. In the embodiment shown in FIG. 5, the at least a part of data in Wi1 [pi1−169, pi1] meets the preset condition C1. As shown in FIG. 16, “” represents 1 byte separately selected when it is determined whether at least a part of data in a window Wi2[pi2−169, pi2] meets a preset condition C2. In FIG. 16, bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1, b2, b3, b4, and b5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any br of b1, b2, b3, b4, and b5 meets 0≦br≦255. b1, b2, b3, b4, and b5 form a 1*5 matrix. In this implementation manner, manners of determining whether at least a part of data in Wi1 and Wi2 meets a preset condition are the same, and therefore, the matrix R is still used. The matrix R is searched for a corresponding value according to the value of b1 and a column in which b1 is located. For example, if b1=66, and b1 is located in a 1st column, a value corresponding to h66,1 is searched for. The matrix R is searched for a corresponding value according to the value of b2 and a column in which b2 is located. For example, if b2=48, and b2 is located in a 2nd column, a value corresponding to h48,2, is searched for. The matrix R is searched for a corresponding value according to the value of b3 and a column in which b3 is located. For example, if b3=99, and b3 is located in a 3rd column, a value corresponding to h99,3 is searched for. The matrix R is searched for a corresponding value according to the value of b4 and a column in which b4 is located. For example, if b4=26, and b4 is located in a 4th column, a value corresponding to h26,4 is searched for. The matrix R is searched for a corresponding value according to the value of b5 and a column in which b5 is located. For example, if b5=90, and b5 is located in a 5th column, a value corresponding to h90,5 is searched for. S2=h66,1+h48,2+h99,3+h26,4+h90,5, and because the matrix R follows binomial distribution, S2 also follows binomial distribution. When S2 is an even number, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2; when S2 is an odd number, the at least a part of data in Wi2[pi2−169, pi2] does not meet the preset condition C2. A probability that S2 is an even number is 1⁄2. In the embodiment shown in FIG. 5, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2. By using the same rule, separately, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. In the implementation manner shown in FIG. 5, the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, 11 bytes are skipped from a point pi5, along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of an 11th byte. As shown in FIG. 6, according to the rule preset on the deduplication server 103, a point pj1 and a window Wj1[pj1−169, pj1] corresponding to the point pj1 are determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 17, Wj1 represents the window Wj1[pj1−169, pj1], and it is determined whether the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1′, a2′, a3′, a4′, and a5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any ar′ of a1′, a2′, a3′, a4′, and a5′ meets 0≦ar′≦255. a1′, a2′, a3′, a4′, and a5′ form a 1*5 matrix. The manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as the manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1, and therefore, the matrix R is still used, and is represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




The matrix R is searched for a corresponding value according to the value of a1′ and a column in which a1′ is located. For example, if a1′=16, and a1′ is located in a 1st column, a value corresponding to h16,1 is searched for. The matrix R is searched for a corresponding value according to the value of a2′ and a column in which a2′ is located. For example, if a2′=98, and a2′ is located in a 2nd column, a value corresponding to h98,2 is searched for. The matrix R is searched for a corresponding value according to the value of a3′ and a column in which a3′ is located. For example, if a3′=56, and a3′ is located in a 3rd column, a value corresponding to h56,3 is searched for. The matrix R is searched for a corresponding value according to the value of a4′ and a column in which a4′ is located. For example, if a4′=36, and a4′ is located in a 4th column, a value corresponding to h36,4 is searched for. The matrix R is searched for a corresponding value according to the value of a5′ and a column in which a5′ is located. For example, if a5′=99, and a5′ is located in a 5th column, a value corresponding to h99,5 is searched for. S1′=h16,1+h98,2+h56,3+h36,4+h99,5, and because the matrix R follows binomial distribution, S1′ also follows binomial distribution. When S1′ is an even number, the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1; when S1′ is an odd number, the at least a part of data in Wj1[pj1−169, pj1] does not meet the preset condition C1. A probability that S1′ is an even number is 1⁄2.
A manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[pj2−169, pj2] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. Selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1′, b2′, b3′, b4′, and b5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any br′ of b1′, b2′, b3′, b4′, and b5′ meets 0≦br′≦255. b1′, b2′, b3′, b4′ and b5′ form a 1*5 matrix. The matrix R the same as that used when it is determined whether the at least a part of data in the window Wi2[pi2−169, pi2] meets the preset condition C2 is used. The matrix R is searched for a corresponding value according to the value of b1′ and a column in which b1′ is located. For example, if b1′=210, and b1′ is located in a 1st column, a value corresponding to h210,1 is searched for. The matrix R is searched for a corresponding value according to the value of b2′ and a column in which b2′ is located. For example, if b2′=156, and b2′ is located in a 2nd column, a value corresponding to h156,2 is searched for. The matrix R is searched for a corresponding value according to the value of b3′ and a column in which b3′ is located. For example, if b3′=144, and b3′ is located in a 3rd column, a value corresponding to h144,3 is searched for. The matrix R is searched for a corresponding value according to the value of b4′ and a column in which b4′ is located. For example, if b4′=60, and b4′ is located in a 4th column, a value corresponding to h60,4 is searched for. The matrix R is searched for a corresponding value according to the value of b5′ and a column in which b5′ is located. For example, if b5′=90, and b5′ is located in a 5th column, a value corresponding to h90,5 is searched for. S2′=h210,1+h156,2+h144,3+h60,4+h90,5. The same as the determining condition of S2, when S1′ is an even number, the at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, and when S2′ is an odd number, the at least a part of data in Wj2[pj2−169, pj2] does not meet the preset condition C2. A probability that S2′ is an even number is 1⁄2.
Similarly, a manner of determining whether at least a part of data in Wi3[pi3−169, pi3] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11, which are not described herein again.
Using the implementation manner shown in FIG. 5 as an example, a method for determining whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition Cz is provided. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. According to a rule preset on a deduplication server 103, a point pi1 and a window Wi1[pi1−169, pi1] corresponding to pi1 are determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1. As shown in FIG. 16, Wi1 represents the window Wi1[pi1−169, pi1], and 5 bytes are selected to determine whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In FIG. 16, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1, a2, a3, a4, and a5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any as of a1, a2, a3, a4, and a5 meets 0≦as≦255. a1, a2, a3, a4, and a5 form a 1*5 matrix. 256*5 random numbers are selected from random numbers that follow binomial distribution to form a matrix R that is represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




256*5 random numbers are selected from random numbers that follow binomial distribution to form a matrix G that is represented as:





  
    (
    
      
        
          
            g
            
              0
              ,
              1
            
          
        
        
          
            g
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              0
              ,
              5
            
          
        
      
      
        
          
            g
            
              1
              ,
              1
            
          
        
        
          
            g
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            g
            
              255
              ,
              5
            
          
        
        
          
            g
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            g
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




According to the value of a1 and a column in which a1 is located, for example, a1=36, and a1 is located in a 1st column, the matrix R is searched for a value corresponding to h36,1, and the matrix G is searched for a value corresponding to g36,1. According to the value of a2 and a column in which a2 is located, for example, a2=48, and a2 is located in a 2nd column, the matrix R is searched for a value corresponding to h48,2, and the matrix G is searched for a value corresponding to g48,2. According to the value of a3 and a column in which a3 is located, for example, a3=26, and a3 is located in a 3rd column, the matrix R is searched for a value corresponding to h26,3, and the matrix G is searched for a value corresponding to g26,3. According to the value of a4 and a column in which a4 is located, for example, a4=26, and a4 is located in a 4th column, the matrix R is searched for a value corresponding to h26,4, and the matrix G is searched for a value corresponding to g26,4. According to the value of a5 and a column in which a5 is located, for example, a5=88, and a5 is located in a 5th column, the matrix R is searched for a value corresponding to h88,5, and the matrix G is searched for a value corresponding to g88,5. S1h=h36,1+h48,2+h26,3+h26,4+h88,5, and because the matrix R follows binomial distribution, S1h also follows binomial distribution. S1g=g36,1+g48,2+g26,3+g26,4+g88,5, and because the matrix G follows binomial distribution, S1g also follows binomial distribution. When one of S1h and S1g is an even number, the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1; when both S1h and S1g are odd numbers, the at least a part of data in Wi1[pi1−169, pi1] does not meet the preset condition C1, and C1 indicates that one of S1h and S1g obtained according to the foregoing method is an even number. Because both S1h and S1g follow binomial distribution, a probability that S1h is an even number is 1⁄2, a probability that S1g is an even number is 1⁄2, and a probability that one of S1h and S1g is an even number is 1−1⁄4=3⁄4. Therefore, a probability that the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1 is 3⁄4. In the embodiment shown in FIG. 5, the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In the implementation manner shown in FIG. 5, for Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11], the windows are the same in size, that is, all the windows have a size of 169 bytes, and meanwhile manners of determining whether at least a part of data in a window meets a preset condition are also the same. For details, refer to the foregoing description of determining whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 16, “” represents 1 byte separately selected when it is determined whether at least a part of data in the window Wi2[pi2−169, pi2] meets a preset condition C2. In FIG. 16, selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1, b2, b3, b4, and b5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any bs of b1, b2, b3, b4, and b5 meets 0≦bs≦255. b1, b2, b3, b4, and b5 form a 1*5 matrix. In this implementation manner, manners of determining whether at least a part of data in each window meets a preset condition are the same, and therefore, the same matrices R and G are still used. According to the value of b1 and a column in which b1 is located, for example, b1=66, and b1 is located in a 1st column, the matrix R is searched for a value corresponding to h66,1, and the matrix G is searched for a value corresponding to g66,1. According to the value of b2 and a column in which b2 is located, for example, b2=48, and b2 is located in a 2nd column, the matrix R is searched for a value corresponding to h48,2, and the matrix G is searched for a value corresponding to g48,2. According to the value of b3 and a column in which b3 is located, for example, b3=99, and b3 is located in a 3rd column, the matrix R is searched for a value corresponding to h99,3, and the matrix G is searched for a value corresponding to g99,3. According to the value of b4 and a column in which b4 is located, for example, b4=26, and b4 is located in a 4th column, the matrix R is searched for a value corresponding to h26,4, and the matrix G is searched for a value corresponding to g26,4. According to the value of b5 and a column in which b5 is located, for example, b5=90, and b5 is located in a 5th column, the matrix R is searched for a value corresponding to h90,5, and the matrix G is searched for a value corresponding to g90,5. S2h=h66,1+h48,2+h99,3+h26,4+h90,5, and because the matrix R follows binomial distribution, S2h also follows binomial distribution. S2g=66,1+g48,2+g99,3+g26,4+g90,5, and because the matrix G follows binomial distribution, S2g also follows binomial distribution. When one of S2h and S2g is an even number, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2; when both S2h and S2g are odd numbers, the at least a part of data in Wi2[pi2−169, pi2] does not meet the preset condition C2. A probability that one of S2h and S2g is an even number is 3⁄4. In the embodiment shown in FIG. 5, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2. By using the same rule, separately, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. In the implementation manner shown in FIG. 5, the at least a part of data in Wi5[i5−169, pi5] does not meet the preset condition C5, 11 bytes are skipped from a point pi5, along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of an 11th byte. As shown in FIG. 6, according to the rule preset on the deduplication server 103, a point pj1 and a window Wj1[pj1−169, pj1] corresponding to the point pj1 are determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 17, Wj1 represents the window Wj1[pj1−169, pj1], and it is determined whether the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1′, a2′, a3′, a4′, and a5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any as′ of a1′, a2′, a3′, a4′, and a5′ meets 0≦as′≦255. a1′, a2′ a3′, a4′, and a5′ form a 1*5 matrix. The matrices R and G the same as those used when it is determined whether the at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1 are used, and are represented as:




   
  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  




and





   
  
    (
    
      
        
          
            g
            
              0
              ,
              1
            
          
        
        
          
            g
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              0
              ,
              5
            
          
        
      
      
        
          
            g
            
              1
              ,
              1
            
          
        
        
          
            g
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            g
            
              255
              ,
              5
            
          
        
        
          
            g
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            g
            
              255
              ,
              5
            
          
        
      
    
    )
  




respectively.

According to the value of a1′ and a column in which a1′ is located, for example, a1′=16, and a1′ is located in a 1st column, the matrix R is searched for a value corresponding to h16,1, and the matrix G is searched for a value corresponding to g16,1. According to the value of a2′ and a column in which a2′ is located, for example, a2′=98, and a2′ is located in a 2nd column, the matrix R is searched for a value corresponding to h98,2, and the matrix G is searched for a value corresponding to g98,2. According to the value of a3′ and a column in which a3′ is located, for example, a3′=56, and a3′ is located in a 3rd column, the matrix R is searched for a value corresponding to h56,3, and the matrix G is searched for a value corresponding to g56,3. According to the value of a4′ and a column in which a4′ is located, for example, a4′=36, and a4′ is located in a 4th column, the matrix R is searched for a value corresponding to h36,4, and the matrix G is searched for a value corresponding to g36,4. According to the value of a5′ and a column in which a5′ is located, for example, a5′=99, and a5′ is located in a 5th column, the matrix R is searched for a value corresponding to h99,5, and the matrix G is searched for a value corresponding to g99,5. S1h′=h16,1+h98,2+h56,3+h36,4+h99,5, and because the matrix R follows binomial distribution, S1h′ also follows binomial distribution. S1g′=g16,1+g98,2+g56,3+g36,4+g99,5, and because the matrix G follows binomial distribution, S1g′ also follows binomial distribution. When one of S1h′ and S1g′ is an even number, the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1; when both S1h′ and S1g′ are odd numbers, the at least a part of data in Wj1[pj1−169, pj1] does not meet the preset condition C1. A probability that one of S1h′ and S1g′ is an even number is 3⁄4.
A manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[pj2−169, pj2] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. In FIG. 17, selected bytes are represented as sequence numbers 170, 128, 86, 44 and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1′, b2′, b3′, b4′, and b5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any bs′ of b1′, b2′, b3′, b4′ and b5′ meets 0≦bs′≦255. b1′, b2′, b3′, b4′, and b5′ form a 1*5 matrix. The matrices R and G the same as those used when it is determined whether the at least a part of data in the window Wi2[pi2−169, pi2] meets the preset condition C2 are used. According to the value of b1′ and a column in which b1′ is located, for example, b1′=210, and b1′ is located in a 1st column, the matrix R is searched for a value corresponding to h210,1, and the matrix G is searched for a value corresponding to g210,1. According to the value of b2′ and a column in which b2′ is located, for example, b2′=156, and b2′ is located in a 2nd column, the matrix R is searched for a value corresponding to h156,2, and the matrix G is searched for a value corresponding to g156,2. According to the value of b3′ and a column in which b3′ is located, for example, b3′=144, and b3′ is located in a 3rd column, the matrix R is searched for a value corresponding to h144,3, and the matrix G is searched for a value corresponding to g144,3. According to the value of b4′ and a column in which b4′ is located, for example, b4′=60, and b4′ is located in a 4th column, the matrix R is searched for a value corresponding to h60,4, and the matrix G is searched for a value corresponding to g60,4. According to the value of b5′ and a column in which b5′ is located, for example, b5′=90, and b5′ is located in a 5th column, the matrix R is searched for a value corresponding to h90,5, and the matrix G is searched for a value corresponding to g90,5. S2h′=h210,1+h156,2+h144,3+h60,4+h90,5, S2g′=g210,1+g56,2+g44,3+g60,4+g90,5. When one of S2h′ and S2g′ is an even number, the at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2; when both S2h′ and S2g′ are odd numbers, the at least a part of data in Wj2[pj2−169, pj2] does not meet the preset condition C2. A probability that one of S2h′ and S2g′ is an even number is 3⁄4.
Similarly, a manner of determining whether at least a part of data in Wi3[pi3−169, pi3] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11, which are not described herein again.
Using the implementation manner shown in FIG. 5 as an example, a method for determining whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition C is provided. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. According to a rule preset on a deduplication server 103, a point pi1 and a window Wi1[pi1−169, pi1] corresponding to pi1 are determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1. As shown in FIG. 16, Wi1 represents the window Wi1[pi1−169, pi1], and 5 bytes are selected to determine whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In FIG. 16, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are regarded as 40 sequential bits, which are represented as a1, a2, a3, a4, . . . , and a40 separately. For any at of a1, a2, a3, a4, . . . , and a40, when at=0, Vat=−1, and when at=1, Vat=1. According to a correspondence between at and Vat, Va1, Va2, Va3, Va4, . . . , and Va40 are generated. 40 random numbers are selected from random numbers that follow normal distribution, and are represented as: h1, h2, h3, h4, . . . , and h40 separately. Sa=Va1*h1+Va2*h2+Va3*h3+Va4*h4+ . . . +Va40*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sa also follows normal distribution. When Sa is a positive number, the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1; when Sa is a negative number or 0, the at least a part of data in Wi1[pi1−169, pi1] does not meet the preset condition C1. A probability that Sa is a positive number is 1⁄2. In the embodiment shown in FIG. 5, the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. As shown in FIG. 16, “” represents 1 byte separately selected when it is determined whether at least a part of data in a window Wi2[pi2−169, pi2] meets a preset condition C2. In FIG. 16, selected bytes are represented as sequence numbers 170, 128, 86, 44 and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are regarded as 40 sequential bits, which are represented as b1, b2, b3, b4, . . . , and b40 separately. For any bt of b1, b2, b3, b4, . . . , and b40, when bt=0, Vbt=−1, and when bt=1, Vbt=1. Vb1, Vb2, Vb3, Vb4, . . . , and Vb40 are generated according to a correspondence between bt and Vbt. A manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wj2[pj2−169, pj2] meets the preset condition C2, and therefore, the same random numbers are used: h1, h2, h3, h4, . . . , and h40. Sb=Vb1*h1+Vb2*h2+Vb3*h3+Vb4*h4+ . . . +Vb40*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sb also follows normal distribution. When Sb is a positive number, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2; when Sb is a negative number or 0, the at least a part of data in Wi2[pi2−169, pi2] does not meet the preset condition C2. A probability that Sb is a positive number is 1⁄2. In the embodiment shown in FIG. 5, the at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2. By using the same rule, separately, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, it is determined whether at least a part of data in Wi6[pi6−169, pi6] meets a preset condition C6, it is determined whether at least a part of data in Wi7[pi7−169, pi7] meets a preset condition C7, it is determined whether at least a part of data in Wi8[pi8−169, pi8] meets a preset condition C8, it is determined whether at least a part of data in Wi9[pi9−169, pi9] meets a preset condition C9, it is determined whether at least a part of data in Wi10[pi10−169, pi10] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[pi11−169, pi11] meets a preset condition C11. In the implementation manner shown in FIG. 5, the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, 11 bytes are skipped from a point pi5 along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of an 11th byte. As shown in FIG. 6, according to the rule preset on the deduplication server 103, a point pj1 and a window Wj1[pj1−169, pj1] corresponding to the point pj1 are determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as the manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, as shown in FIG. 17, Wj1 represents the window Wj1[pj1−169, pj1], and 5 bytes are selected to determine whether the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are regarded as 40 sequential bits, which are represented as a1′, a2′, a3′, a4′, . . . , and a40′ separately. For any a1′ of a1′, a2′, a3′, a4′, . . . , and a40′, when a1′=0, Vat′=−1, and when at′=1, Vat′=1. Va1′, Va2′, Va3′, Va4′, . . . , and Va40′ are generated according to a correspondence between at′ and Vat′. The manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as the manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1, and therefore, the same random numbers are used: h1, h2, h3, h4, . . . , and h40. Sa′=Va1′*h1+Va2′*h2+Va3′*h3+Va4′*h4+ . . . +Va40′*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sa′ also follows normal distribution. When Sa′ is a positive number, the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1; when Sa′ is a negative number or 0, the at least a part of data in Wj1[pj1−169, pj1] does not meet the preset condition C1. A probability that Sa′ is a positive number is 1⁄2.
The manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2. Therefore, as shown in FIG. 17, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[pj2−169, pj2] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. In FIG. 17, selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are regarded as 40 sequential bits, which are represented as b1′, b2′, b3′, b4′, . . . , and b40′ separately. For any b1′ of b1′, b2′, b3′, b4′, . . . , and b40′, when bt′=0, Vbt′=−1, and when bt′=1, Vbt′=1. Vb1′, Vb2′, Vb3′, Vb4′, . . . , and Vb40′ are generated according to a correspondence between b1′ and Vbt′. The manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as the manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, and therefore, the same random numbers are used: h1, h2, h3, h4, . . . , and h40. Sb′=Vb1′*h1+Vb2′*h2+Vb3′*h3+Vb4′*h4+ . . . +Vb40′*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sb′ also follows normal distribution. When Sb′ is a positive number, the at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2; when Sb′ is a negative number or 0, the at least a part of data in Wj2[pj2−169, pj2] does not meet the preset condition C2. A probability that Sb′ is a positive number is 1⁄2.
Similarly, a manner of determining whether at least a part of data in Wi3[pi3−169, pi3] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets the preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets the preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets the preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets the preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets the preset condition C11, which are not described herein again.
Still using the implementation manner shown in FIG. 5 as an example, a method for determining whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition Cz is provided. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. According to a rule preset on a deduplication server 103, a point pi1 and a window Wi1[pi1−169, pi1] corresponding to pi1 are determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[pi1−169, pi1] meets a preset condition C1. As shown in FIG. 16, Wi1 represents the window Wi1[pi1−169, pi1], and 5 bytes are selected to determine whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. In FIG. 16, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. Each of the bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 is converted into 1 decimal number, the range of which is 0−(2^40−1). An even distribution random number generator is used to generate 1 designated value for each decimal number in 0−(2^40−1), and a correspondence R between each decimal number in 0−(2^40−1) and the designated value is recorded. Once being designated, a designated value corresponding to a decimal number remains unchanged, and the designated value follows even distribution. If the designated value is an even number, the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1; if the designated value is an odd number, the at least a part of data in Wi1[pi1−169, pi1] does not meet the preset condition C1. C1 represents that the designated value obtained according to the foregoing method is an even number. Because a probability that a random number in even distribution is an even number is 1⁄2, a probability that the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1 is 1⁄2. In the implementation manner shown in FIG. 5, by using the same rule, separately, it is determined whether at least a part of data in Wi2[pi2−169, pi2] meets a preset condition C2, it is determined whether at least a part of data in Wi3[pi3−169, pi3] meets a preset condition C3, it is determined whether at least a part of data in Wi4[pi4−169, pi4] meets a preset condition C4, and it is determined whether at least a part of data in Wi5[pi5−169, pi5] meets a preset condition C5, which are not described herein again.
When the at least a part of data in Wi5[pi5−169, pi5] does not meet the preset condition C5, 11 bytes are skipped from a point pi5 along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of an 11th byte. As shown in FIG. 6, according to the rule preset on the deduplication server 103, a point pj1 and a window Wj1[pj1−169, pj1] corresponding to the point pj1 are determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[pj1−169, pj1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[pi1−169, pi1] meets the preset condition C1. Therefore, the same correspondence R between each decimal number in 0−(2^40−1) and a designated value is used. As shown in FIG. 17, Wj1 represents the window Wj1[pj1−169, pj1], and 5 bytes are selected to determine whether the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1. In FIG. 17, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes “”. Each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 is converted into 1 decimal number, and R is searched for a designated value corresponding to the decimal number. If the designated value is an even number, the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1; if the designated value is an odd number, the at least a part of data in Wj1[pj1−169, pj1] does not meet the preset condition C1. Because a probability that a random number in even distribution is an even number is 1⁄2, a probability that the at least a part of data in Wj1[pj1−169, pj1] meets the preset condition C1 is 1⁄2. Similarly, a manner of determining whether at least a part of data in Wi2[pi2−169, pi2] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[pj2−169, pj2] meets the preset condition C2, and a manner of determining whether at least a part of data in Wi3[pi3−169, pi3] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[pj3−169, pj3] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[pj4−169, pj4] meets the preset condition C4, it is determined whether at least a part of data in Wj5[pj5−169, pj5] meets the preset condition C5, it is determined whether at least a part of data in Wj6[pj6−169, pj6] meets a preset condition C6, it is determined whether at least a part of data in Wj7[pj7−169, pj7] meets a preset condition C7, it is determined whether at least a part of data in Wj8[pj8−169, pj8] meets a preset condition C8, it is determined whether at least a part of data in Wj9[pj9−169, pj9] meets a preset condition C9, it is determined whether at least a part of data in Wj10[pj10−169, pj10] meets a preset condition C10, and it is determined whether at least a part of data in Wj11[pj11−169, pj11] meets a preset condition C11, which are not described herein again.
The deduplication server 103 in the embodiment of the present invention shown in FIG. 1 refers to an apparatus that can implement a technical solution described in an embodiment of the present invention, and as shown in FIG. 18, usually includes a central processing unit, a primary memory, and an input/output interface. The central processing unit, the primary memory, and the input/output interface communicate with each other. The main memory stores an executable instruction, and the central processing unit executes the executable instruction stored in the primary memory, so as to perform a specific function, for example, searching for a data stream dividing point described in FIG. 4 to FIG. 17 in the embodiments of the present invention. Therefore, as shown in FIG. 19, according to the embodiments of the present invention shown in FIG. 4 to FIG. 17, for the deduplication server 103, a rule is preset on the deduplication server 103, where the rule is: for a potential dividing point k, determining M points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers. The deduplication server 103 includes a determining unit 1901 and a judging and processing unit 1902. The determining unit 1901 is configured to perform step (a): (a) determining a point piz and a window Wiz[piz−Az, piz+Bz] corresponding to the point piz for a current potential dividing point ki according to the rule, where i and z are integers, and 1≦z≦M. The judging and processing unit 1902 is configured to: determine whether at least a part of data in the window Wiz[piz−Az, piz+Bz] meets a preset condition Cz;
when the at least a part of data in the window Wiz[piz−Az, piz+Bz] does not meet the preset condition Cz, skip N minimum units U for searching for a data stream dividing point from the point piz along a direction of searching for a data stream dividing point, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥+∥(ki−pix)∥), so as to obtain a new potential dividing point, where the determining unit performs step (a) for the new potential dividing point; and when at least a part of data in each window Wix[pix−Ax, pix+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, select the current potential dividing point ki as a data stream dividing point.
Further, the rule further includes that at least two points pe and pf meet conditions Ae=Af, Be=Bf, and Ce=Cf. Further, the rule further includes: relative to the potential dividing point k, the at least two points pe and pf are in a direction opposite to the direction of searching for a data stream dividing point.
Further, the rule further includes that a distance between the at least two points pe and pf is 1 U.
Further, the judging and processing unit 1902 is specifically configured to determine, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. Specifically, the judging and processing unit 1902 is specifically configured to determine, by using a hash function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz. Specifically, that the judging and processing unit 1902 is specifically configured to determine, by using a random function, whether the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz specifically includes:
selecting F bytes in the window Wiz[piz−Az, piz+Bz], and using the F bytes repeatedly H times to obtain F*H bytes in total, where F≧1, each byte is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the F*H bytes, bits corresponding to the F*H bytes may be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




where when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1, where am,n represents any one of am,1, . . . , and am,8, a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the F*H bytes, the matrix Va is represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers are selected from random numbers following normal distribution to form a matrix R, the matrix R is represented as:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers in an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8, Sa1, Sa2, . . . , and SaF*H are obtained in a same way, a quantity K of values greater than 0 among Sa1, Sa2, . . . , and SaF*H is counted, and when K is an even number, the at least a part of data in the window Wiz[piz−Az, piz+Bz] meets the preset condition Cz.

Further, the judging and processing unit 1902 is configured to: when the at least a part of data in the window Wiz[piz−Az, piz+Bz] does not meet the preset condition Cz, skip the N minimum units U for searching for a data stream dividing point from the point piz along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and the determining unit 1901 performs step (a) for the new potential dividing point, where and according to the rule, a left boundary of a window Wic[pic−Ac, pic+Bc] corresponding to a point pic that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[piz−Az, piz+Bz] or a left boundary of a window Wic[pic−Ac, pic+Bc] falls within a range of the window Wiz[piz−Az, piz+Bz], where the point pic determined for the new potential dividing point is a point ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M points that are determined for the new potential dividing point according to the rule.
According to the method for searching for a data stream dividing point based on a server in the embodiments of the present invention shown in FIG. 4 to FIG. 17, a point pix and a window Wix[pix−Ax, pix+Bx] corresponding to the point pix are determined for a potential dividing point ki, where x indicates consecutive natural numbers from 1 to M separately, and M≧2. It may be determined in parallel whether at least a part of data in each window of M windows meets a preset condition Cx, or it may be determined sequentially whether at least a part of data in windows meets a preset condition, or it may be first determined that at least a part of data in a window Wi1[pi1−A1, pi1+B1] meets a preset condition C1, then it is determined that at least a part of data in Wi2[pi2−A2, pi2+B2] meets a preset condition C2, until it is determined that at least a part of data in Wim[pim−Am, pim+Bm] meets a preset condition Cm. Other windows in this embodiment are determined in a same manner as the above, which is not described again.
In addition, according to the embodiments of the present invention shown in FIG. 4 to FIG. 17, in actual applications, a rule is preset on the deduplication server 103, where the rule is: for a potential dividing point k, determining M points px, a window Wx[px−Ax, px+Bx] corresponding to the point px, and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to M separately, and M≧2. In the preset rule, A1, A2, A3, . . . , and Am may be not all equal, B1, B2, B3, . . . , and Bm may be not all equal, and C1, C2, C3, . . . , and CM may also be not all the same. In the implementation manner shown in FIG. 5, for windows Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−169, pi11], the windows are the same in size, that is, all the windows have a size of 169 bytes, and meanwhile manners of determining whether at least a part of data in a window meets a preset condition are also the same. For details, refer to the foregoing description of determining whether the at least a part of data in Wi1[pi1−169, pi1] meets the preset condition C1. However, in the implementation manner shown in FIG. 11, the windows Wi1[pi1−169, pi1], Wi2[pi2−169, pi2], Wi3[pi3−169, pi3], Wi4[pi4−169, pi4], Wi5[pi5−169, pi5], Wi6[pi6−169, pi6], Wi7[pi7−169, pi7], Wi8[pi8−169, pi8], Wi9[pi9−169, pi9], Wi10[pi10−169, pi10], and Wi11[pi11−182, pi11] may be different in size, and meanwhile the manners of determining whether at least a part of data in a window meets a preset condition may also be different. In all the embodiments, according to the rule preset on the deduplication server 103, a manner of determining whether at least a part of data in the window Wi1 meets the preset condition C1 is certainly the same as a manner of determining whether at least a part of data in a window Wj1, meets the preset condition C1, a manner of determining whether at least a part of data in Wi2 meets the preset condition C2 is certainly the same as a manner of determining whether at least a part of data in Wj2 meets the preset condition C2, . . . , and a manner of determining whether at least a part of data in a window WiM meets a preset condition CM is certainly the same as a manner of determining whether at least a part of data in a window WjM meets the preset condition CM, which are not described herein again. Meanwhile, according to the embodiments of the present invention shown in FIG. 4 to FIG. 17, although M=11 is used as an example, the value of M is not limited to 11 according to an actual requirement, and a person skilled in the art determines the value of M according to the description in the embodiments of the present invention.
According to the embodiments of the present invention shown in FIG. 4 to FIG. 17, the rule is preset on the deduplication server 103, ka, ki, kj, kl, and km are potential dividing points obtained in the search for a dividing point along a direction of searching for a data stream dividing point, and ka, ki, kj, kl, and km all follow the rule. The window Wx[px−Ax, px+Bx] in this embodiment of the present invention represents a specific range, and data is selected in the specific range to determine whether the data meets the preset condition Cx. Specifically, in the specific range, a part of data may be selected or all data may be selected to determine whether the data meets the preset condition Cx. Reference may be made to the window Wx[px−Ax, px+Bx] for the concept of a window specifically used in this embodiment of the present invention, which is not described herein again.
According to the embodiments of the present invention shown in FIG. 4 to FIG. 17, in the window Wx[px−Ax, px+Bx], (px−Ax) and (px+Bx) represent two boundaries of the window Wx[px−Ax, px+Bx], where (px−Ax) represents a boundary, which is in a direction opposite to the direction of searching for a data stream dividing point relative to the point px, of the window Wx[px−Ax, px+Bx], and (px+Bx) represents a boundary, which is in the direction of searching for a data stream dividing point relative to the point px, of the window Wx[px−Ax, px+Bx]. Specifically, in the embodiment of the present invention, the direction of searching for a data stream dividing point shown in FIG. 3 to FIG. 15 is from left to right; therefore, (px−Ax) represents a boundary (that is, a left boundary), which is in a direction opposite to the direction of searching for a data stream dividing point relative to the point px, of the window Wx[px−Ax, px+Bx], and (px+Bx) represents a boundary (that is, a right boundary), which is in the direction of searching for a data stream dividing point relative to the point px, of the window Wx[px−Ax, px+Bx]. If the direction of searching for a data stream dividing point shown in FIG. 3 to FIG. 15 is from right to left, (px−Ax) represents a boundary (that is, a right boundary), which is in a direction opposite to the direction of searching for a data stream dividing point relative to the point px, of the window Wx[px−Ax, px+Bx], and (px+Bx) represents a boundary (that is, a left boundary), which is in the direction of searching for a data stream dividing point relative to the point px, of the window Wx[px−Ax, px+Bx].
A person of ordinary skill in the art may be aware that, in conjunction with various exemplary units and algorithm steps described in the embodiments of the present invention, a key feature in the embodiments of the present invention may be combined with other technologies and presented in a more complex form; however, the key feature of the present invention is still included. An alternative dividing point may be used in a real environment. For example, in an implementation manner, according to a rule preset on a deduplication server 103, 11 points px are determined for a potential dividing point ki, where x indicates consecutive natural numbers from 1 to 11, and a window Wx[px−Ax, px+Bx] corresponding to px and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx] are determined. When at least a part of data in each window Wx[px−Ax, px+Bx] of 11 windows meets the preset condition Cx, the potential dividing point ki is a data stream dividing point. When no dividing point is found when a set maximum data chunk is exceeded, a preset rule for the alternative point may be used in this case. The preset rule for the alternative point is similar to the rule preset on the deduplication server 103, and the preset rule for the alternative point is: for example, for a potential dividing point ki, 10 points px are determined, where x indicates consecutive natural numbers from 1 to 10, and a window Wx[px−Ax, px+Bx] corresponding to px and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx] are determined. When at least a part of data in each window Wx[px−Ax, px+Bx] of 10 windows meets the preset condition Cx, the potential dividing point ki is a data stream dividing point; when no data stream dividing point is found when a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
A rule is preset on the deduplication server 103, and in the rule, M points are determined for a potential dividing point k. It is not necessarily required that there be a potential dividing point k in advance, and the potential dividing point k may be determined by using the determined M points.
An embodiment of the present invention provides a method for searching for a data stream dividing point based on a deduplication server, which, as shown in FIG. 20, includes:
A rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining M windows Wx[px−Ax, px+Bx] and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers. In the implementation manner shown in FIG. 3, about a value of M, in one implementation manner, a value of M*U is not greater than a preset maximum distance between two adjacent data stream dividing points, that is, a preset maximum length of a data chunk. It is determined whether at least a part of data in a window Wz[k−Az, k+Bz] meets a preset condition Cz, where, z is an integer, 1≦z≦M, and (k−Az) and (k+Bz) separately represent two boundaries of the window Wz. When it is determined that at least a part of data in any one window Wz[k−Az, k+Bz] does not meet the preset condition Cz, N bytes are skipped from the potential dividing point k along a direction of searching for a data stream dividing point, where N≦∥Bz∥+maxx(∥Ax∥). ∥Bz∥ represents an absolute value of Bz in Wz[k−Az, k+Bz], maxx(∥Ax∥) represents a maximum value among the absolute value of Ax in the M windows, and a principle of determining a value of N is specifically introduced in the following embodiments. When it is determined that at least a part of data in each window Wx[k−Ax, k+Bx] of the M windows meets the preset condition Cx, the potential dividing point k is a data stream dividing point.
Specifically, for a current potential dividing point ki, the following steps are performed according to the rule:
Step 2001: Determine a corresponding window Wiz[ki−Az, ki+Bz] for the current potential dividing point ki according to the rule, where i and z are integers, and 1≦z≦M.
Step 2002: Determine whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz;
when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skip N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along the direction of searching for a data stream dividing point, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a new potential dividing point, and perform step 2001; and
when at least a part of data in each window Wix[ki−Ax, ki+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, select the current potential dividing point ki as a data stream dividing point.
Further, the rule further includes that at least two windows Wie[ki−Ae, ki+Be] and Wif[ki−Af, ki+Bf] meet conditions |Ae+Be|=|Af+Bf|, and Ce=Cf. Further, the rule further includes that Ae and Af are positive integers. Still further, the rule further includes Ae−1=Af and Be+1=Bf. |Ae+Be| represents a size of the window Wie, and |Af+Bf| represents a size of the window Wif.
Further, the determining whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz specifically includes: determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz. Still further, the determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz is specifically: determining, by using a hash function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.
When the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, the N minimum units U for searching for a data stream dividing point are skipped from the current potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point. According to the rule, a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[ki−Ac, ki+Bc] or a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point falls within a range of the window Wiz[ki−Az, ki+Bz], where the window Wic[ki−Ac, ki+Bc] determined for the new potential dividing point is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M windows that are determined for the new potential dividing point according to the rule.
In this embodiment of the present invention, a data stream dividing point is searched for by determining whether at least a part of data in a window of M windows meets a preset condition, and when the at least a part of data in the window does not meet the preset condition, a length of N*U is skipped, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a next potential dividing point, thereby improving efficiency of searching for a data stream dividing point.
In a process of eliminating duplicate data, to ensure an even size of a data chunk, a size of an average data chunk (also referred to as an average chunk) is considered. That is, while limits on a size of a minimum data chunk and a size of a maximum data chunk are met, the size of the average data chunks is determined to ensure an even size of an obtained data chunk. A probability (represented as P(n)) of finding a data stream dividing point depends on two factors, that is, the quantity M of the windows Wx[k−Ax, k+Bx] and a probability that at least a part of data in the window Wx[k−Ax, k+Bx] meets a preset condition, where the former affects a length for skipping, the latter affects a probability of skipping, and the two together affect the size of the average chunk. Generally, when the size of the average chunk is fixed, as the quantity of Wx[k−Ax, k+Bx] increases, the probability that at least a part of data in a single window Wx[k−Ax, k+Bx] meets a preset condition also increases. For example, a rule is preset on the deduplication server 103, and the rule is: for a potential dividing point k, determining 11 windows Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to 11 separately, and a probability that at least a part of data in any window Wx[k−Ax, k+Bx] of the 11 windows meets a preset condition is 1⁄2. Another group of rules preset on the deduplication server 103 is: determining 24 windows Wx[k−Ax, k+Bx] for the potential dividing point k, where x indicates consecutive natural numbers from 1 to 24 separately, and a probability that at least a part of data in any window Wx[k−Ax, k+Bx] of the 24 windows meets the preset condition Cx is 3⁄4. For the setting of a probability that at least a part of data in a specific window Wx[k−Ax, k+Bx] meets a preset condition, reference may be made to the description of the part of determining whether at least a part of data in the window Wx[k−Ax, k+Bx] meets a preset condition. P(n) depends on the two factors, that is, the quantity M of windows Wx[k−Ax, k+Bx] and the probability that at least a part of data in the window Wx[k−Ax, k+Bx] meets a preset condition, and P(n) represents: a probability that no data stream dividing point is found after n minimum units for searching for a data stream dividing point in a search from a start position or a previous data stream dividing point of a data stream. A process of calculating P(n) that depends on the two factors is actually an n-step Fibonacci sequence, which is described below in detail. After P(n) is obtained, 1−P(n) is a distribution function of a data stream dividing point, and (1−P(n))−(1−P(n−1))=P(n−1)−P(n) is a probability that a data stream dividing point is found at a distance of n minimum units for searching for a data stream dividing point, that is, a density function of a data stream dividing point. Integration




  
    ∑
    
      n
      =
      
        
          4
          *
        
        ⁢
        1024
      
    
    
      
        12
        *
      
      ⁢
      1024
    
  
  ⁢
  
    n
    ×
    
      (
      
        
          P
          ⁡
          
            (
            
              n
              -
              1
            
            )
          
        
        -
        
          P
          ⁡
          
            (
            n
            )
          
        
      
      )
    
  




may be performed according to the density function of a data stream dividing point, so as to obtain an expected length of a data stream dividing point, that is, the size of the average chunk, where 4*1024 (bytes) represents a length of the minimum data chunk, and 12*1024 (bytes) represents a length of the maximum data chunk.

On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 21, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to 11, and Ax and Bx are integers. A1=169, B1=0; A2=170, B2=−1; A3=171, B3=−2; A4=172, B4=−3; A5=173, B5=−4; A6=174, B6=−5; A7=175, B7=−6; A8=176, B8=−7; A9=177, B9=−8; A10=178, B10=−9; A11=179, B11=−10. C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. Therefore, the 11 windows are W1[k−169, k], W2[k−170, k−1], W3[k−171, k−2], W4[k−172, k−3], W5[k−173, k−4], W6[k−174, k−5], W7[k−175, k−6], W8[k−176, k−7], W9[k−177, k−8], W10[k−178, k−9], and W11[k−179, k−10]. ka is a data stream dividing point, and a direction of searching for a data stream dividing point shown in FIG. 21 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki. According to the rule preset on the deduplication server 103, a window Wix[ki−Ax, ki+Bx] is determined for the potential dividing point ki, and in this embodiment, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 21, 11 windows are determined for the potential dividing point ki, and are Wi1[ki−169, ki], Wi2[ki−170, k1−1], Wi3[ki−171, ki−2], Wi4[ki−172, ki−3], Wi5[ki−173, ki−4], Wi6[ki−174, ki−5], Wi7[ki−175, ki−6], Wi8[ki−176, ki−7], Wi9[ki−177, ki−8], Wi10[ki−178, ki−9], and Wi11[ki−179, ki−10] separately. It is determined whether at least a part of data in Wi1[ki−169, ki] meets the preset condition C1, it is determined whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2, it is determined whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3, it is determined whether at least a part of data in Wi4[ki−172, ki−3] meets the preset condition C4, it is determined whether at least a part of data in Wi5[ki−173, ki−4] meets the preset condition C5, it is determined whether at least a part of data in Wi6[ki−174, ki−5] meets the preset condition C6, it is determined whether at least a part of data in Wi7[ki−175, ki−6] meets the preset condition C7, it is determined whether at least a part of data in Wi8[ki−176, ki−7] meets the preset condition C8, it is determined whether at least a part of data in Wi9[ki−177, ki−8] meets the preset condition C9, it is determined whether at least a part of data in Wi10[ki−178, ki−9] meets the preset condition C10, and it is determined whether at least a part of data in Wi11[ki−179, ki−10] meets the preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, for example, Wi5[ki−173, ki−4] shown in FIG. 22, N bytes are skipped from the potential dividing point ki along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B5∥+maxx(∥Ax∥). In an implementation manner shown in FIG. 22, the N bytes that are skipped are not greater than 183 bytes, and in this embodiment, N=7, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point here is represented as kj here. According to the implementation manner shown in FIG. 21, a rule is preset on the deduplication server 103, where the rule is: determining a window Wjx[kj−Ax, k+Bx] for the potential dividing point kj, where in this embodiment, x indicates consecutive natural numbers from 1 to 11 separately. 11 windows are determined for the potential dividing point kj, and are Wj1[kj−169, kj], Wj2[kj−170, kj−1], Wj3[kj−171, kj−2], Wj4[kj−172, kj−3], Wj5[kj−173, kj−4], Wj6[kj−174, kj−5], Wj7[kj−175, kj−6], Wj8[kj−176, kj−7], Wj9[kj−177, kj−8], Wj10[kj−178, kj−9], and Wj11[kj−179, kj−10] separately. As shown in FIG. 22, when the 11th window Wj11[kj−179, kj−10] is determined for the potential dividing point, to ensure that a range between the potential dividing point ki and the potential dividing point kj completely falls within a determining range, in this implementation manner, it may be ensured that a left boundary of the window Wj11[kj−179, kj−10] coincides with a right boundary (ki−4) of the window Wi5[ki−173, ki−4], or falls within a range of the window Wi5[ki−173, ki−4], where the window Wj11[kj−179, kj−10] is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of the 11 windows that are determined for the potential dividing point kj according to the rule. Therefore, within such a limit, when at least a part of data in the window Wi5[ki−173, ki−4] does not meet the preset condition C5, a distance for skipping from the potential dividing point ki along the direction of searching for a data stream dividing point is not greater than ∥B5∥+maxx(∥Ax∥). It is determined whether at least a part of data in Wj1[kj−169, kj] meets the preset condition C1, it is determined whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2, it is determined whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets the preset condition C8, it is determined whether at least a part of data in W9[kj−177, kj−8] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj−10] meets the preset condition C11. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and according to the rule preset on the deduplication server 103, it is determined whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, a next potential dividing point is obtained in a manner the same as that of ki, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
In the implementation manner shown in FIG. 21, according to the rule preset on the deduplication server 103, starting from determining whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1, when it is determined the at least a part of data in Wi1[ki−169, ki], the at least a part of data in Wi2[ki−170, ki−1], the at least a part of data in Wi3[ki−171, ki−2], and the at least a part of data in Wi4[ki−172, ki−3] meet the preset conditions C1, C2, C3, and C4 respectively, and it is determined that the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 6 bytes are skipped from the potential dividing point ki along the direction of searching for a data stream dividing point, and a new potential dividing point is obtained at an end position of a 6th byte. For differentiation from other potential dividing points, the new potential dividing point is represented as kg here. According to the rule preset on the deduplication server 103, 11 windows are determined for the potential dividing point kg, and are Wg1[kg−169, kg], Wg2[kg−170, kg−1], Wg3[kg−171, kg−2], Wg4[kg−172, kg−3], Wg5[kg−173, kg−4], Wg6[kg−174, kg−5], Wg7[kg−175, kg−6], Wg8[kg−176, kg−7], Wg9[kg−177, kg−8], Wg10[kg−178, kg−9], and Wg11[kg−179, kg−10] separately. It is determined whether at least a part of data in Wg1[kg−169, kg] meets the preset condition C1, it is determined whether at least a part of data in Wg2[kg−170, kg−1] meets the preset condition C2, it is determined whether at least a part of data in Wg3[kg−171, kg−2] meets the preset condition C3, it is determined whether at least a part of data in Wg4[kg−172, kg−3] meets the preset condition C4, it is determined whether at least a part of data in Wg5[kg−173, kg−4] meets the preset condition C5, it is determined whether at least a part of data in Wg6[kg−174, kg−5] meets a preset condition C6, it is determined whether at least a part of data in Wg7[kg−175, kg−6] meets a preset condition C7, it is determined whether at least a part of data in Wg8[kg−176, kg−7] meets a preset condition C8, it is determined whether at least a part of data in Wg9[kg−177, kg−8] meets a preset condition C9, it is determined whether at least a part of data in Wg10[kg−178, kg−9] meets a preset condition C10, and it is determined whether at least a part of data in Wg11[kg−179, kg−10] meets a preset condition C11. The window Wg11[kg−179, kg−10] coincides with the window Wi5[ki−173, ki−4], and C5=C11; therefore, when it is determined that the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, a potential dividing point kg obtained by skipping T bytes from the potential dividing point ki along the direction of searching for a data stream dividing point still does not meet a condition for serving as a data stream dividing point. Therefore, if repeated calculation exists when 6 bytes are skipped from the potential dividing point ki along the direction of searching for a data stream dividing point, then repeated calculation can be reduced and efficiency is higher when 7 bytes are skipped from the potential dividing point ki along the direction of searching for a data stream dividing point. Therefore, a speed of searching for a data stream dividing point is increased. When a probability that at least a part of data in the window Wx[k−Ax, k+Bx] that is determined according to the preset rule meets the preset condition Cx is 1⁄2, that is, a probability of executing skipping is 1⁄2, at most ∥B11∥+|A11=189 bytes can be skipped each time.
In this implementation manner, a preset rule is that: 11 windows Wx[k−Ax, k+Bx] are determined for a potential dividing point k and at least a part of data in the window Wx[k−Ax, k+Bx] meets a preset condition Cx, where a probability that at least a part of data in Wx[k−Ax, k+Bx] meets the preset condition Cx is 1⁄2, where x indicates consecutive natural numbers from 1 to 11 separately, and Ax and Bx are integers. A1=169, B1=0; A2=170, B2=−1; A3=171, B3=−2; A4=172, B4=−3; A5=173, B5=−4; A6=174, B6=−5; A7=175, B7=−6; A8=176, B8=−7; A9=177, B9=−8; A10=178, B10=−9; A11=179, B11=−10. C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. That is, 11 windows are selected for the potential dividing point k, and the 11 windows are consecutive; P(n) can be calculated by using the two factors, that is, the quantity of windows and the probability that at least a part of data in the window Wx[px−Ax, px+Bx] meets the preset condition Cx. A manner of selecting the 11 windows and the determining that at least a part of data in each window of the 11 windows meets the preset condition Cx follow the rule preset on the deduplication server 103, and therefore, whether the potential dividing point k is a data stream dividing point depends on whether it exists that at least a part of data in each window of 11 consecutive windows meets the preset condition Cx. A gap between two bytes is referred to as one point. P(n) represents a probability that 11 consecutive windows meeting a condition do not exist among n consecutive windows, that is, a probability that no data stream dividing point exists. After a minimum chunk size of 4 KB is skipped from a file header/previous dividing point, a 4086th point is found by going back by 10 bytes in a direction opposite to the direction of searching for a data stream dividing point, and no data stream dividing point exists at the point; therefore, P(4086)=1, and P(4087)=1, . . . , P(4095)=1, and so on. At an 4096th point, that is, a point which is used to obtain the minimum chunk, with a probability of (1⁄2)^11, at least a part of data in each window of the 11 windows meets the preset condition Cx. Hence, with a probability of (1⁄2)^11, a data stream dividing point exists; with a probability of 1−(1⁄2)^11, no data stream dividing point exists; therefore P(4096)=1−(1⁄2)^11.
As shown in FIG. 35, in an nth window, there may be 12 cases of obtaining P(n) by means of recursion.
Case 1: With a probability of 1⁄2, at least a part of data in the nth window does not meet a preset condition; in this case, with a probability of P(n−1), 11 consecutive windows do not exist among (n−1) windows before the nth window, where at least a part of data in each window of the 11 consecutive windows meets a preset condition. Therefore, P(n) includes 1⁄2*P(n−1). A case in which the at least a part of data in the nth window does not meet the preset condition, and 11 consecutive windows exist among the (n−1) windows before the nth window, where at least a part of data in each window of the 11 consecutive windows meets the preset condition, is not related to P(n).
Case 2: With a probability of 1⁄2, at least a part of data in the nth window meets a preset condition, and with the probability of 1⁄2, at least a part of data in an (n−1)th window does not meet a preset condition; in this case, with a probability of P(n−2), 11 consecutive windows do not exist among (n−2) windows before the (n−1)th window, where at least a part of data in each window of the 11 consecutive windows meets a preset condition. Therefore, P(n) includes 1⁄2*1⁄2*P(n−2). A case in which the at least a part of data in the nth window meets the preset condition, the at least a part of data in the (n−1)th point window does not meet the preset condition, and 11 consecutive windows exist among the (n−2) windows before the (n−1)th window, where at least a part of data in each window of the 11 consecutive windows meets the preset condition, is not related to P(n).
According to the foregoing description, case 11: With a probability of (1⁄2)^10, at least a part of data in nth to (n−9)th windows meets a preset condition, and with a probability of 1⁄2, at least a part of data in an (n−10)th window does not meet a preset condition; in this case, with a probability of P(n−11), 11 consecutive windows do not exist among (n−11) windows before the (n−10)th window, where at least a part of data in each window of the 11 consecutive windows meets a preset condition. Therefore, P(n) includes (1⁄2)^10*1⁄2*P(n−11). A case in which the at least a part of data in the nth to (n−9)th windows meets the preset condition, the at least a part of data in the (n−10)th window does not meet the preset condition, and 11 consecutive windows exist among the (n−11) windows before the (n−10)th window, where at least a part of data in each window of the 11 consecutive windows meets the preset condition, is not related to P(n).
Case 12: With a probability of (1⁄2)^11, at least a part of data in nth to (n−10) windows meets a preset condition is, and this case is not related to P(n).
Therefore, P(n)=1⁄2*P(n−1)+(1⁄2)^2*P(n−2)+ . . . +(1⁄2)^11*P(n−11). Another preset rule is: for a potential dividing point k, 24 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx] are determined, where x indicates consecutive natural numbers from 1 to 11, A1=169, B1=0; A2=170, B2=−1; A3=171, B3=−2; A4=172, B4=−3; A5=173, B5=−4; A6=174, B6=−5; A7=175, B7=−6; A8=176, B8=−7; A9=177, B9=−8; A10=178, B10=−9; A11=179, B11=−10, . . . , and A24=192, Bj4=−23. C1=C2=C3=C4=C5=C6=C7=C8=C9= . . . =C24. A probability that at least a part of data in the window Wx[k−Ax, k+Bx] meets the preset condition Cx is 3⁄4, and P(n) can be calculated by using the two factors, that is, the quantity of windows and the probability that at least a part of data in the window Wx[px−Ax, px+Bx] meets the preset condition Cx.
Therefore, whether the potential dividing point k is a data stream dividing point depends on whether it exists that at least a part of data in each window of the 24 consecutive windows meets the preset condition Cx, and calculation can be performed by using the following formulas:

P(1)=1,P(2), . . . ,P(23)=1,P(24)=1−(3⁄4)^24, and

P(n)=1⁄4*P(n−1)+1⁄4*(3⁄4)*P(n−2)+ . . . +1⁄4*(3⁄4)^23*P(n−24).

After calculation, P(5*1024)=0.78, P(11*1024)=0.17, and P(12*1024)=0.13. That is, no data stream dividing point is found with a probability of 13% after a search proceeds to a point at a distance of 12 KB from a start position/previous data stream dividing point of a data stream, and forced division is performed. A density function of a data stream dividing point is obtained by using this probability, and after integration, it is obtained that on average, a data stream dividing point is found after a search proceeds to a point at a distance about 7.6 KB from the start position/previous data stream dividing point of the data stream, that is, an average chunk length is about 7.6 KB. Different from that at least a part of data in 11 consecutive windows meets a preset condition with a probability of 1⁄2, a conventional CDC algorithm can achieve an effect of an average chunk length being 7.6 KB only when one window meets a condition with a probability of 1⁄2^12.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 23, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to 11, and Ax and Bx are integers. A probability that at least a part of data in the window Wx[k−Ax, k+Bx] meets the preset condition Cx is 1⁄2. A1=171, B1=−2; A2=172, B2=−3; A3=173, B3=−4; A4=174, B4=−5; A5=175, B5=−6; A6=176, B6=−7; A7=177, B7=−8; A8=178, B8=−9; A9=179, B9=−10; A10=170, B10=−1; A11=169, B11=0. C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. ka is a data stream dividing point, and a direction of searching for a data stream dividing point shown in FIG. 23 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki. According to the rule preset on the deduplication server 103, for the potential dividing point ki, Wix[ki−Ax, ki+Bx] and the preset condition Cx corresponding to the window Wix[ki−Ax, ki+Bx] are determined, where x indicates consecutive natural numbers from 1 to 11. Determined 11 windows are Wi1[ki−171, ki−2], Wi2[ki−172, ki−3], Wi3[ki−173, ki−4], Wi4[ki−174, ki−5], Wi5[ki−175, ki−6], Wi6[ki−176, ki−7], Wi7[ki−177, ki−8], Wi8[ki−178, ki−9], Wi9[ki−179, ki−10], Wi10[ki−170, ki−1], and Wi11[ki−169, ki] separately. It is determined whether at least a part of data in Wi1[ki−171, ki−2] meets the preset condition C1, it is determined whether at least a part of data in Wi2 [ki−172, ki−3] meets the preset condition C2, it is determined whether at least a part of data in Wi3[ki−173, ki−4] meets the preset condition C3, it is determined whether at least a part of data in Wi4[ki−174, ki−5] meets the preset condition C4, it is determined whether at least a part of data in Wi5[ki−175, ki−6] meets the preset condition C5, it is determined whether at least a part of data in Wi6[ki−176, ki−7] meets the preset condition C6, it is determined whether at least a part of data in Wi7[ki−177, ki−8] meets the preset condition C7, it is determined whether at least a part of data in Wi8[ki−178, ki−9] meets the preset condition C8, it is determined whether at least a part of data in Wi9[ki−179, ki−10] meets the preset condition C9, it is determined whether at least a part of data in Wi10[ki−170, ki−1] meets the preset condition C10, and it is determined whether at least a part of data in Wi11[ki−169, ki] meets the preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7, meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, as shown in FIG. 24, that the at least a part of data in Wi3[pi3−169, pi3] does not meet the preset condition C3, 11 bytes are skipped from a point pi3 along a direction of searching for a data stream dividing point is used as an example for description. As shown in FIG. 24, when it is determined that W3 does not meet the preset condition C3, from ki that serves as a start point, N bytes are skipped along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B3∥+maxx(∥Ax∥). In this embodiment, N=7, and a next potential dividing point is obtained at an end position of a 7th byte. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. According to the rule preset on the deduplication server 103, for the potential dividing point kj, 11 windows Wjx[kj−Ax, kj+Bx] are determined, and are Wj1[kj−171, kj−2], Wj2[kj−172, kj−3], Wj3[kj−173, kj−4], Wj4[kj−174, kj−5], Wj5[kj−175, kj−6], Wj6[kj−176, kj−7], Wj7 [kj−177, kj−8], Wj8[kj−178, kj−9], Wj9[kj−179, kj−10], Wj10[kj−170, kj−1], and Wj11[kj−169, kj] separately. It is determined whether at least a part of data in Wj1[kj−171, kj−2] meets the preset condition C1, it is determined whether at least a part of data in Wj2[kj−172, kj−3] meets the preset condition C2, it is determined whether at least a part of data in Wj3[kj−173, kj−4] meets the preset condition C3, it is determined whether at least a part of data in Wj4[kj−174, kj−5] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−175, kj−6] meets the preset condition C5, it is determined whether at least a part of data in Wj6 [kj−176, kj−7] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−177, kj−8] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−178, kj−9] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−179, kj−10] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−170, kj−1] meets the preset condition C10 and it is determined whether at least a part of data in Wj11[kj−169, kj] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and according to the rule preset on the deduplication server 103, it is determined whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, a next potential dividing point is obtained in a manner the same as that of ki, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point. Certainly, implementation of the method is restricted by a length of the maximum data chunk and a size of a file forming the data stream, which is not described herein again.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 25, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to 11. A1=166, B1=3; A2=167, B2=2; A3=168, B3=1; A4=169, B4=0; A5=170, B5=−1; A6=171, B6=−2; A7=172, B7=−3; A8=173, B8=−4; A9=174, B9=−5; A10=175, B10=−6; A11=176, B11=−7. C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11, and 11 windows are W1[k−166, k+3], W2[k−167, k+2], W3[k−168, k+1], W4[k−169, k], W5[k−170, k−1], W6[k−171, k−2], W7[k−172, k−3], W8[k−173, k−4], W9[k−174, k−5], W10[k−175, k−6], and W11 [k−176, k−7] separately. ka is a data stream dividing point, and a direction of searching for a data stream dividing point shown in FIG. 25 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, for the potential dividing point ki, 11 windows Wix[k−Ax, k+Bx] and the preset condition Cx corresponding to the window Wix[k−Ax, k+Bx] are determined, where x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 25, for the potential dividing point ki, the 11 windows that are determined are Wi1[ki−166, ki+3], Wi2[ki−167, ki+2], Wi3[ki−168, ki+1], Wi4[ki−169, ki], Wi5[ki−170, ki−1], Wi6[ki−171, ki−2], Wi7[ki−172, ki−3], Wi8[ki−173, ki−4], Wi9[ki−174, ki−5], Wi10[ki−175, ki−6], and Wi11[ki−176, ki−7] separately. It is determined whether at least a part of data in Wi1[ki−166, ki+3] meets the preset condition C1, it is determined whether at least a part of data in Wi2[ki−167, ki+2] meets the preset condition C2, it is determined whether at least a part of data in Wi3[ki−168, ki+1] meets the preset condition C3, it is determined whether at least a part of data in Wi4[ki−169, ki] meets the preset condition C4, it is determined whether at least a part of data in Wi5[ki−170, ki−1] meets the preset condition C5, it is determined whether at least a part of data in Wi6[ki−171, ki−2] meets the preset condition C6, it is determined whether at least a part of data in Wi7 Wi7[ki−172, ki−3] meets the preset condition C7, it is determined whether at least a part of data in Wi8[ki−173, ki−4] meets the preset condition C8, it is determined whether at least a part of data in Wi9[ki−174, ki−5] meets the preset condition C9, it is determined whether at least a part of data in Wi10[ki−175, ki−6] meets the preset condition C10, and it is determined whether at least a part of data in Wi11[ki−176, ki−7] meets the preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5, meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, for example, Wi7[ki−172, ki−3] shown in FIG. 26, N bytes are skipped from the potential dividing point ki along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B7∥+maxx(∥Ax∥). In an implementation manner shown in FIG. 26, the N bytes which are skipped are not greater than 185 bytes, and in this embodiment, N=5, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. According to the rule preset on the deduplication server 103 in the implementation manner shown in FIG. 25, for the potential dividing point kj, 11 windows are determined, and are Wj1[kj−166, kj+3], Wj2[kj−167, kj+2], Wj3[kj−168, kj+1], Wj4[kj−169, kj], Wj5[kj−170, kj−1], Wj6[kj−171, kj−2], Wj7[kj−172, kj−3], Wj8[kj−173, kj−4], Wj9[kj−174, kj−5], Wj10[kj−175, kj−6], and Wj11[kj−176, kj−7] separately. It is determined whether at least a part of data in Wj1[kj−166, k+3] meets the preset condition C1, it is determined whether at least a part of data in Wj2[kj−167, kj+2] meets the preset condition C2, it is determined whether at least a part of data in Wj3[kj−168, kj+1] meets the preset condition C3, it is determined whether at least a part of data in Wj4[kj−169, kj] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−170, kj−1] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−171, kj−2] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−172, kj−3] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−173, kj−4] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−174, kj−5] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−175, kj−6] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−176, kj−7] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and according to the rule preset on the deduplication server 103, it is determined whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, a next potential dividing point is obtained in a manner the same as that of ki, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
On the basis of the search for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 27, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to 11. A1=169, B1=0; A2=170, B2=−1; A3=171, B3=−2; A4=172, B4=−3; A5=173, B5=−4; A6=174, B6=−5; A7=175, B7=−6; A8=176, B8=−7; A9=177, B9=−8; A10=168, B10=1; A11=179, B11=3. C1=C2=C3=C4=C5=C6=C7=C8=C9=C10C11, and 11 windows are W1[k−169, k], W2[k−170, k−1], W3[k−171, k−2], W4[k−172, k−3], W5[k−173, k−4], W6[k−174, k−5], W7[k−175, k−6], W8[k−176, k−7], W9[k−177, k−8], W10[k−168, k+1], and W11 [k−179, k+3] separately. ka is a data stream dividing point, and a direction of searching for a data stream dividing point shown in FIG. 27 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, for the potential dividing point ki, a window Wix[ki−Ax, ki+Bx] is determined, where x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 27, for the potential dividing point ki, 11 windows that are determined are Wi1[ki−169, ki], Wi2[ki−170, ki−1], Wi3[ki−171, ki−2], Wi4[ki−172, ki−3], Wi5[ki−173, ki−4], Wi6[ki−174, ki−5], Wi7[ki−175, ki−6], Wi8[ki−176, ki−7], Wi9[ki−177, ki−8], Wi10[ki−168, ki+1], and Wi11[ki−179, ki+3] separately. It is determined whether at least a part of data in Wi1[ki−169, ki+1] meets the preset condition C1, it is determined whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2, it is determined whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3, it is determined whether at least a part of data in Wi4[ki−172, ki−3] meets the preset condition C4, it is determined whether at least a part of data in Wi5[ki−173, ki−4] meets the preset condition C5, it is determined whether at least a part of data in Wi6[ki−174, ki−5] meets the preset condition C6, it is determined whether at least a part of data in Wi7[ki−175, ki−6] meets the preset condition C7, it is determined whether at least a part of data in Wi8[ki−176, ki−7] meets the preset condition C8, it is determined whether at least a part of data in Wi9[ki−177, ki−8] meets the preset condition C9, it is determined whether at least a part of data in Wi10[ki−168, ki+1] meets the preset condition C10, and it is determined whether at least a part of data in Wi11[ki−179, ki+3] meets the preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When it is determined that the at least a part of data in the window Wi11 does not meet the preset condition C11, 1 byte is skipped from the potential dividing point kj along the direction of searching for a data stream dividing point, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as ki here. When the at least a part of data in any window the 10 windows Wi1, Wi2, Wi3, Wi4, Wi5, Wi6, Wi7, Wi8, Wi9, and Wi10 does not meet the corresponding preset condition, for example, Wi4 [ki−172, ki−3] shown in FIG. 28, N bytes are skipped from the point ki along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B4∥+maxx(∥Ax∥). In an implementation manner shown in FIG. 28, the N bytes that are skipped are not greater than 182 bytes, and in this embodiment, N=6, so as to obtain a new potential dividing point. For differentiation from the potential dividing point ki, the new potential dividing point is represented as kj here. According the rule preset on the deduplication server 103 in the implementation manner shown in FIG. 27, windows determined for the potential dividing point kj are Wj1[kj−169, kj], Wj2[kj−170, kj−1], Wj3[kj−171, kj−2], Wj4[kj−172, kj−3], Wj5[kj−173, kj−4], Wj6[kj−174, kj−5], Wj7[kj−175, kj−6], Wj8[kj−176, kj−7], Wj9[kj−177, kj−8], Wj10[kj−168, kj+1], and Wj11 [kj−179, kj+3] separately. It is determined whether at least a part of data in Wj1[kj−169, kj] meets the preset condition C1, it is determined whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2, it is determined whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−168, kj+1] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj+3] meets the preset condition C11. Certainly, in this embodiment of the present invention, the rule is also followed when it is determined whether the potential dividing point ka is a data stream dividing point, specific implementation is not described again, and reference may be made to the description of determining the potential dividing point ki. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wj9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point, and data between kj and ka forms 1 data chunk. Meanwhile, a minimum chunk size of 4 KB is skipped in a manner the same as that of ka to obtain a next potential dividing point, and according to the rule preset on the deduplication server 103, it is determined whether the next potential dividing point is a data stream dividing point. When it is determined that the potential dividing point kj is not a data stream dividing point, a next potential dividing point is obtained in a manner the same as that of ki, and it is determined, according to the rule preset on the deduplication server 103 and the foregoing method, whether the next potential dividing point is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
On the basis of the searching for a data stream dividing point shown in FIG. 3, in an implementation manner shown in FIG. 29, a rule is preset on a deduplication server 103, where the rule is: for a potential dividing point k, determining 11 windows Wx[px−Ax, px+Bx] and a preset condition Cx corresponding to the window Wx[px−Ax, px+Bx], where x indicates consecutive natural numbers from 1 to 11 separately, where a probability that at least a part of data in the window Wx[px−Ax, px+Bx] meets a preset condition is 1⁄2. A1=169, B1=0; A2=171, B2=−2; A3=173, B3=−4; A4=175, B4=−6; A5=177, B5=−8; A6=179, B6=−10; A7=181, B7=−12; A8=183, B8=−14; A9=185, B9=−16; A10=187, B10=−18; A11=189, B11=−20. C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11, and the 11 windows are W1[k−169, k], W2[k−171, k−2], W3[k−173, k−4], W4[k−175, k−6], W5[k−177, k−8], W6[k−179, k−10], W7[k−181, k−12], W8 [k−183, k−14], W9[k−185, k−16], W10[k−187, k−18], and W11[k−189, k−20] separately. ka is a data stream dividing point, and a direction of searching for a data stream dividing point shown in FIG. 29 is from left to right. After a minimum data chunk of 4 KB is skipped from the data stream dividing point ka, an end position of the minimum data chunk of 4 KB serves as a next potential dividing point ki, and a point pix is determined for the potential dividing point ki. In this embodiment, according to the rule preset on the deduplication server 103, x indicates consecutive natural numbers from 1 to 11 separately. In the implementation manner shown in FIG. 29, according to the preset rule, 11 windows determined for the potential dividing point ki are Wi1[ki−169, ki], Wi2[ki−171, ki−2], Wi3[ki−173, ki−4], Wi4[ki−175, ki−6], Wi5[ki−177, ki−8], Wi6[ki−179, ki−10], Wi7[ki−181, ki−12], Wi8[ki−183, ki−14], Wi9[ki−185, ki−16], Wi10[ki−187, ki−18], and Wi11[ki−189, ki−20] separately. It is determined whether at least a part of data in Wi1[ki−169, ki] meets the preset condition C1, it is determined whether at least a part of data in Wi2[ki−171, ki−2] meets the preset condition C2, it is determined whether at least a part of data in Wi3[ki−173, ki−4] meets the preset condition C3, it is determined whether at least a part of data in Wi4[ki−175, ki−6] meets the preset condition C4, it is determined whether at least a part of data in Wi5[ki−177, ki−8] meets the preset condition C5, it is determined whether at least a part of data in Wi6[ki−179, ki−10] meets the preset condition C6, it is determined whether at least a part of data in Wi7[ki−181, ki−12] meets the preset condition C7, it is determined whether at least a part of data in Wi8[ki−183, ki−14] meets the preset condition C8, it is determined whether at least a part of data in Wi9[ki−185, ki−16] meets the preset condition C9, it is determined whether at least a part of data in Wi10[ki−187, ki−18] meets the preset condition C10, and it is determined whether at least a part of data in Wi11[ki−189, ki−20] meets the preset condition C11. When it is determined that the at least a part of data in the window Wi1 meets the preset condition C1, the at least a part of data in the window Wi2 meets the preset condition C2, the at least a part of data in the window Wi3 meets the preset condition C3, the at least a part of data in the window Wi4 meets the preset condition C4, the at least a part of data in the window Wi5 meets the preset condition C5, the at least a part of data in the window Wi6 meets the preset condition C6, the at least a part of data in the window Wi7 meets the preset condition C7, the at least a part of data in the window Wi8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wi10 meets the preset condition C10, and the at least a part of data in the window Wi11 meets the preset condition C11, the current potential dividing point ki is a data stream dividing point. When the at least a part of data in any window of the 11 windows does not meet the corresponding preset condition, for example, as shown in FIG. 30, the at least a part of data in Wi4[ki−175, ki−6] does not meet the preset condition C4, a next potential dividing point is selected. For differentiation from the potential dividing point ki, the next potential dividing point is represented as kj here, where kj is located on the right of ki, and a distance between kj and ki is 1 byte. As shown in FIG. 30, according to the rule preset on the deduplication server 103, for the potential dividing point kj, 11 windows are determined, and are Wj1[kj−169, kj], Wj2[kj−171, kj−2], Wj3[kj−173, kj−4], Wj4[kj−175, kj−6], Wj5[kj−177, kj−8], Wj6[ki−179, kj−10], Wj7[kj−181, kj−12], Wj8[kj−183, kj−14], Wj9[kj−185, kj−16], Wj10 [kj−187, kj−18], and Wj11[kj−189, kj−20] separately, where C1=C2=C3=C4=C5=C6=C7=C8=C9=C10=C11. It is determined whether at least a part of data in Wj1[kj−169, kj] meets the preset condition C1, it is determined whether at least a part of data in Wj2[kj−171, kj−2] meets the preset condition C2, it is determined whether at least a part of data in W3[kj−173, kj−4] meets the preset condition C3, it is determined whether at least a part of data in Wj4[kj−175, kj−6] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−177, kj−8] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−179, kj−10] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−181, kj−12] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−183, kj−14] meets the preset condition C8, it is determined whether at least a part of data in W9[kj−185, kj−16] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−187, kj−18] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−189, kj−20] meets the preset condition C11. When it is determined that the at least a part of data in the window Wj1 meets the preset condition C1, the at least a part of data in the window Wj2 meets the preset condition C2, the at least a part of data in the window Wj3 meets the preset condition C3, the at least a part of data in the window Wj4 meets the preset condition C4, the at least a part of data in the window Wj5 meets the preset condition C5, the at least a part of data in the window Wj6 meets the preset condition C6, the at least a part of data in the window Wj7 meets the preset condition C7, the at least a part of data in the window Wj8 meets the preset condition C8, the at least a part of data in the window Wi9 meets the preset condition C9, the at least a part of data in the window Wj10 meets the preset condition C10, and the at least a part of data in the window Wj11 meets the preset condition C11, the current potential dividing point kj is a data stream dividing point. When it is determined that the at least a part of data in any window of the windows Wj1, Wj2, Wj3, Wj4, Wj5, Wj6, Wj7, Wj8, Wj9, Wj10, and Wj11 does not meet a preset condition, for example, as shown in FIG. 31, when the at least a part of data in Wj3[kj−173, kj−4] does not meet the preset condition C3, kj is located on the right of ki and N bytes are skipped from ki along the direction of searching for a data stream dividing point, where the N bytes are not greater than ∥B4∥+maxx(∥Ax∥). In the implementation manner shown in FIG. 28, the N bytes are not greater than 195 bytes, and in this embodiment, N=15, so as to obtain a next potential dividing point. For differentiation from the potential dividing points ki and kj, the next potential dividing point is represented as ki. According to the rule preset on the deduplication server 103 in the implementation manner in FIG. 29, for the potential dividing point kl, 11 windows are determined, and are Wl1[kl−169, kl], Wl2[kl−171, kl−2], Wl3[kl−173, kl−4], Wl4[kl−175, kl−6], W15[kl−177, kl−8], Wl6[kl−179, kl−10], Wl7[kl−181, kl−12], Wl8[kl−183, kl−14], Wl9 [kl−185, kl−16], Wl10[kl−187, kl−18], and Wl11[kl−189, kl−20] separately. It is determined whether at least a part of data in Wl1[kl−169, kl] meets the preset condition C1, it is determined whether at least a part of data in Wl2[kl−171, kl−2] meets the preset condition C2, it is determined whether at least a part of data in Wl3[kl−173, kl−4] meets the preset condition C3, it is determined whether at least a part of data in Wl4[kl−175, kl−6] meets the preset condition C4, it is determined whether at least a part of data in Wl5, [kl−177, kl−8] meets the preset condition C5, it is determined whether at least a part of data in Wl6, [kl−179, kl−10] meets the preset condition C6, it is determined whether at least a part of data in Wl7[kl−181, kl−12] meets the preset condition C7, it is determined whether at least a part of data in Wl8[kl−183, kl−14] meets the preset condition C8, it is determined whether at least a part of data in Wl9, [kl−185, kl−16] meets the preset condition C9, it is determined whether at least a part of data in Wl10[kl−187, kl−18]meets the preset condition C10, and it is determined whether at least a part of data in Wl11[kl−189, kl−20] meets the preset condition C11. When it is determined that the at least a part of data in the window Wl1 meets the preset condition C1, the at least a part of data in the window Wl2 meets the preset condition C2, the at least a part of data in the window Wl3 meets the preset condition C3, the at least a part of data in the window Wl4 meets the preset condition C4, the at least a part of data in the window Wl5 meets the preset condition C5, the at least a part of data in the window Wl6 meets the preset condition C6, the at least a part of data in the window Wl7 meets the preset condition C7, the at least a part of data in the window Wl8 meets the preset condition C8, the at least a part of data in the window Wl9 meets the preset condition C9, the at least a part of data in the window Wl10 meets the preset condition C10, and the at least a part of data in the window Wl11 meets the preset condition C11, the current potential dividing point kl is a data stream dividing point. When the at least a part of data in any window of the windows Wl1, Wl2, Wl3Wl4, Wl5, Wl6, Wl7, Wl8, Wl9, Wl10, and Wl11 does not meet a preset condition, a next potential dividing point is selected. For differentiation from the potential dividing points ki, kj, and kl, the next potential dividing point is represented as km, where km is located on the right of kl, and a distance between km and kl is 1 byte. According to the rule preset on the deduplication server 103 in the embodiment shown in FIG. 29, 11 windows determined for the potential dividing point km are Wm1[km−169, km], Wm2[km−171, km−2], Wm3[km−173, km−4], Wm4[km−175, km−6], Wm5[km−177, km−8], Wm6[km−179, km−10], Wm7[km−181, km−12], Wm8[km−183, km−14], Wm9[km−185, km−16], Wm10[km−187, km−18], and Wm11[km−189, km−20] separately. It is determined whether at least a part of data in Wm1[km−169, km] meets the preset condition C1, it is determined whether at least a part of data in Wm2[km−171, km−2] meets the preset condition C2, it is determined whether at least a part of data in Wm3[km−173, km−4] meets the preset condition C3, it is determined whether at least a part of data in Wm4[km−175, km−6] meets the preset condition C4, it is determined whether at least a part of data in Wm5[km−177, km−8] meets the preset condition C5, it is determined whether at least a part of data in Wm6[km−179, km−10] meets the preset condition C6, it is determined whether at least a part of data in Wm7[km−181, km−12] meets the preset condition C7, it is determined whether at least a part of data in Wm8[km−183, km−14] meets the preset condition C8, it is determined whether at least a part of data in Wm9[km−185, km−16] meets the preset condition C9, it is determined whether at least a part of data in Wm10[km−187, km−18] meets the preset condition C10, and it is determined whether at least a part of data in Wm11[km−189, km−20] meets the preset condition C11. When it is determined that the at least a part of data in the window Wm1 meets the preset condition C1, the at least a part of data in the window Wm2 meets the preset condition C2, the at least a part of data in the window Wm3 meets the preset condition C3, the at least a part of data in the window Wm4 meets the preset condition C4, the at least a part of data in the window Wm5 meets the preset condition C5, the at least a part of data in the window Wm6 meets the preset condition C6, the at least a part of data in the window Wm7 meets the preset condition C7, the at least a part of data in the window Wm8 meets the preset condition C8, the at least a part of data in the window Wm9 meets the preset condition C9, the at least a part of data in the window Wm10 meets the preset condition C10, and the at least a part of data in the window Wm11 meets the preset condition C11, the current potential dividing point km is a data stream dividing point. When the at least a part of data in any window does not meet a preset condition, skipping is executed according to the solution described above to obtain a next potential dividing point, and it is determined whether the next potential dividing point is a data stream dividing point.
An embodiment of the present invention provides a method for determining whether at least a part of data in a window Wiz[ki−Az, ki+Bz] meets a preset condition Cz. In this embodiment, it is determined, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz, and the implementation manner shown in FIG. 21 is used as an example. According to a rule preset on a deduplication server 103, a window Wi1[ki−169, ki] is determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[ki−169, ki] meets a preset condition C1. As shown in FIG. 32, Wi1 represents the window Wi1[ki−169, ki], and 5 bytes are selected to determine whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 32, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              255
              ,
              1
            
          
        
        
          
            a
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




where when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1, where am,n represents any one of am,1, . . . , and am,8, and a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
          
        
      
    
    )
  
  ,




A large quantity of random numbers is selected to form a matrix. Once being formed, the matrix formed by the random numbers remains unchanged. For example, 255*8 random numbers are selected from random numbers that follow specific distribution (normal distribution is used as an example here) to form a matrix R:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




where random numbers of an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8. Sa1, Sa2, . . . , and Sa255 are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sa1, Sa2, . . . , and Sa255 is counted. Because the matrix R follows normal distribution, Sam still follows normal distribution as the matrix R does. According to a probability theory, a probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sa1, Sa2, . . . , and Sa255 is greater than 0 is 1⁄2, and therefore, K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sa1, Sa2, . . . , and Sa255 is an even number; a probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. When K is an odd number, it indicates that the at least a part of data in W1[ki−169, ki] does not meet the preset condition C1. C1 here refers to that the quantity K, which is obtained according to the foregoing manner, of values greater than 0 among Sa1, Sa2, . . . , and Sa255 is an even number. In the implementation manner shown in FIG. 21, for Wi1[ki−169, ki], Wi2[ki−170, ki−1], Wi3[ki−171, ki−2], Wi4[ki−172, ki−3], Wi5[ki−173, ki−4], Wi6[ki−174, ki−5], Wi7[ki−175, ki−6], Wi8[ki−176, ki−7], Wi9[ki−177, ki−8], Wi10[ki−178, ki−9], and Wi11 [ki−179, ki−10], the windows are the same in size, that is, all the windows have a size of 169 bytes, and meanwhile, manners of determining whether at least a part of data in a window meets a preset condition are also the same. For details, refer to the foregoing description of determining whether the at least a part of data in Wi1[kj−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 32, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi2[ki−170, ki−1] meets a preset condition C2, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as bm,1, . . . , and bm,8, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:





  
    (
    
      
        
          
            b
            
              1
              ,
              1
            
          
        
        
          
            b
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            b
            
              1
              ,
              8
            
          
        
      
      
        
          
            b
            
              2
              ,
              1
            
          
        
        
          
            b
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            b
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            b
            
              255
              ,
              1
            
          
        
        
          
            b
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            b
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




where when bm,n=1, Vbm,n=1, and when bm,n, =0, Vbm,n=−1, where bm,n represents any one of bm,1, . . . , and bm,8, and a matrix Vb is obtained according to a conversion relationship between bm,n and Vbm,n from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
          
        
      
    
    )
  
  .




A manner of determining whether at least a part of data in Wi1[ki−169, ki] meets a preset condition is the same as a manner of determining whether at least a part of data in the window Wi2[ki−170, ki−1] meets a preset condition; therefore the matrix R is used:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




and random numbers of an mth row of the matrix Vb and the mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sbm=Vbm,1*hm,1+Vbm,2*hm,2+ . . . +Vbm,8*hm,8. Sb1, Sb2, . . . , and Sb255 are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sb1, Sb2, . . . , and Sb255 is counted. Because the matrix R follows normal distribution, Sbm still follows normal distribution as the matrix R does. According to the probability theory, the probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sb1, Sb2, . . . , and Sb255 is greater than 0 is 1⁄2, and therefore, K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sb1, Sb2, . . . , and Sb255 is an even number; the probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2. When K is an odd number, it indicates that the at least a part of data in Wi2[ki−170, ki−1] does not meet the preset condition C2. C2 here refers to that the quantity K, which is obtained according to the foregoing manner, of values greater than 0 among Sb1, Sb2, . . . , and Sb255 is an even number. In the implementation manner shown in FIG. 21, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2.

Therefore, as shown in FIG. 32, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi3[ki−171, ki−2] meets a preset condition C3, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Then, the method for determining whether at least a part of data in the windows Wi1[ki−169, ki] and Wi2[ki−170, ki−1] meets a preset condition is used to determine whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3. In the implementation manner shown in FIG. 21, the at least a part of data in Wi3[ki−171, ki−2] meets the preset condition. As shown in FIG. 32, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi4 [ki−172, ki−3] meets a preset condition C4, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Then, the method for determining whether at least a part of data in the windows Wi1[ki−169, ki], Wi2[ki−170, ki−1], and Wi3[ki−171, ki−2] meets a preset condition is used to determine whether the at least a part of data in Wi4[ki−172, ki−3] meets the preset condition C4. In the implementation manner shown in FIG. 21, the at least a part of data in Wi4 [ki−172, ki−3] meets the preset condition C4. As shown in FIG. 32, “” represents 1 byte selected when it is determined whether at least a part of data in the window Wi5[ki−173, ki−4] meets a preset condition C5, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Then, the method for determining whether at least a part of data in the windows Wi1[ki−169, ki], Wi2[ki−170, ki−1], Wi3[ki−171, ki−2], and Wi4[ki−172, ki−3] meets a preset condition is used to determine whether the at least a part of data in Wi5[ki−173, ki−4] meets the preset condition C5. In the implementation manner shown in FIG. 21, the at least a part of data in Wi4[ki−173, ki−4] does not meet the preset condition C5.
When the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 7 bytes are skipped from a point pi5 along a direction of searching for a data stream dividing point, and a next potential dividing point kj is obtained at an end position of a 7th byte. As shown in FIG. 22, according to the rule preset on the deduplication server 103, a window Wj1[kj−169, kj] is determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[kj−169, kj] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 33, Wj1 represents a window, and 5 bytes are selected to determine whether the at least a part of data in the window meets the preset condition C1. In FIG. 33, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as am,1′, . . . , and am,8′, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
            ′
          
        
        
          
            a
            
              1
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
            ′
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
            ′
          
        
        
          
            a
            
              2
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
            ′
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              255
              ,
              1
            
            ′
          
        
        
          
            a
            
              255
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            a
            
              255
              ,
              8
            
            ′
          
        
      
    
    )
  
  ,




where when am,n′=1, Vam,n′=1, and when am,n′=0, Vam,n′=−1, where am,n′ represents any one of am,n′, . . . , and am,8′, and a matrix Va′ is obtained according to a conversion relationship between am,n′ and Vam,n′ from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
            ′
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
            ′
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
            ′
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
            ′
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
            ′
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
            ′
          
        
      
    
    )
  
  .




A manner of determining whether at least a part of data in the window meets a preset condition is the same as a manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets a preset condition. Therefore the matrix R is used:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  ,




and random numbers of an mth row of the matrix Va′ and the mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam′=Vam,1′*hm,1+Vam,2′*hm,2+ . . . +Vam,8′*hm,8. Sa1′, Sa2′, . . . , and Sa255′ are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sa1′, Sa2′, . . . , and Sa255′ is counted. Because the matrix R follows normal distribution, Sam′ still follows normal distribution as the matrix R does. According to the probability theory, the probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sa1′, Sa2′, . . . , and Sa255′ is greater than 0 is 1⁄2, and therefore K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sa1′, Sa2′, . . . , and Sa255′ is an even number; the probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1. When K is an odd number, it indicates that the at least a part of data in Wj1, [kj−169, kj] does not meet the preset condition C1.

A manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2 [kj−170, kj−1] meets the preset condition C2. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[kj−170, kj−1] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. Selected 5 bytes of data are used repeatedly 51 times to obtain 255 bytes in total, so as to increase randomness. Each byte thereof is formed by 8 bits, which are denoted as bm,1′, . . . , and bm,8′, representing the 1st bit to the 8th bit of an mth byte in the 255 bytes, and therefore, bits corresponding to the 255 bytes may be represented as:




  
    (
    
      
        
          
            b
            
              1
              ,
              1
            
            ′
          
        
        
          
            b
            
              1
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            b
            
              1
              ,
              8
            
            ′
          
        
      
      
        
          
            b
            
              2
              ,
              1
            
            ′
          
        
        
          
            b
            
              2
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            b
            
              2
              ,
              8
            
            ′
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            b
            
              255
              ,
              1
            
            ′
          
        
        
          
            b
            
              255
              ,
              2
            
            ′
          
        
        
          ...
        
        
          
            b
            
              255
              ,
              8
            
            ′
          
        
      
    
    )
  
  ,




where when bm,n′=1, Vbm,n′=1, and when bm,n′=0, Vbm,n′=−1, where bm,n′ represents any one of bm,1′, . . . , and bm,8′, and a matrix Vb′ is obtained according to a conversion relationship between bm,n′ and Vbm,n′ from the bits corresponding to the 255 bytes, and may be represented as:





  
    (
    
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              1
            
          
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                b
                ⁢
                
                  
                
                ⁢
                255
              
              ,
              8
            
          
        
      
    
    )
  
  .




A manner of determining whether at least a part of data in the window Wi2[ki−170, ki−1] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C1, and therefore the matrix R is still used:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              1
            
          
        
        
          
            h
            
              255
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              8
            
          
        
      
    
    )
  
  .




Random numbers of an mth row of the matrix Vb′ and the mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sbm′=Vbm,1′*hm,1+bm,2′*hm,2+ . . . +Vbm,8*hm,8. Sb1′, Sb2′, . . . , and Sb255′ are obtained according to the method, and a quantity K of values meeting a specific condition (being greater than 0 is used as an example here) among Sb1′, Sb2′, . . . , and Sb255′ is counted. Because the matrix R follows normal distribution, Sbm′ still follows normal distribution as the matrix R does. According to the probability theory, the probability that a random number in normal distribution is greater than 0 is 1⁄2; a probability that each value among Sb1′, Sb2′, . . . , and Sb255′ is greater than 0 is 1⁄2, and therefore K meets binomial distribution: P(k=n)=C255n(1⁄2)n(1⁄2)255−n=C255n(1⁄2)255. According to a counting result, it is determined whether the quantity K of values greater than 0 among Sb1′, Sb2′, . . . , and Sb255′ is an even number; the probability that a random number in binomial distribution is an even number is 1⁄2, and therefore, K meets a condition with a probability of 1⁄2. When K is an even number, it indicates that the at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2. When K is an odd number, it indicates that the at least a part of data in Wj2[kj−170, kj−1] does not meet the preset condition C2. Similarly, a manner of determining whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets a preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets a preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets a preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets a preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets a preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj−10] meets a preset condition C11, which are not described herein again.

In this embodiment, it is determined, by using a random function, whether at least a part of data in a window Wiz[ki−Az, ki+Bz] meets a preset condition Cz. The implementation manner shown in FIG. 21 is still used as an example. According to a rule preset on a deduplication server 103, a window Wi1[ki−169, ki] is determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. As shown in FIG. 32, Wi1 represents the window Wi1[ki−169, ki], and 5 bytes are selected to determine whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 32, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes “”. In one implementation manner, a hash function is used to calculate the selected 5 bytes, and values obtained by means of calculation by using the hash function are in fixed and even distribution. If a value obtained by means of calculation by using the hash function is an even number, it is determined that the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. That is, C1 represents that a value obtained according to the foregoing manner and by means of calculation by using the hash function is an even number. Therefore, a probability that at least a part of data in Wi1[ki−169, ki] meets a preset condition is 1⁄2. In the implementation manner shown in FIG. 21, it is determined, by using a hash function, whether at least a part of data in Wi2[ki−170, ki−1] meets a preset condition C2, whether at least a part of data in Wi3[ki−171, ki−2] meets a preset condition C3, whether at least a part of data in Wi4[ki−172, ki−3] meets a preset condition C4, and whether at least a part of data in Wi5[ki−173, ki−4] meets a preset condition C5. For specific implementation, reference may be made to the description of the manner of determining, by using a hash function, whether at least a part of data in Wi1[ki−169, ki] meets the preset condition C1 in the implementation manner shown in FIG. 21, which is not described herein again.
When the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 7 bytes are skipped from the potential dividing point ki along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of a 7th byte. As shown in FIG. 22, according to the rule preset on the deduplication server 103, a window Wj1[kj−169, kj] is determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj[kj−169, kj] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 33, Wj1 represents the window Wj1[kj−169, kj], and 5 bytes are selected to determine whether the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1. In FIG. 33, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes “”. The 5 bytes selected from the window Wj1[kj−169, kj] are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1. In FIG. 33, a manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[kj−170, kj−1] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes “”. Selected 5 bytes are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2. In FIG. 33, a manner of determining whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj3[kj−171, kj−2] meets the preset condition C3, and there are 42 bytes between two adjacent selected bytes “”. Selected 5 bytes are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3. In FIG. 33, a manner of determining whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4 is the same as a manner of determining whether at least a part of data in the window Wi4[ki−172, ki−3] meets the preset condition C4. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj4[kj−172, kj−3] meets the preset condition C4, and there are 42 bytes between two adjacent selected bytes “”. Selected 5 bytes are calculated by using a hash function. If an obtained value is an even number, the at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4. According to the foregoing method, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets a preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets a preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets a preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets a preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets a preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj−10] meets a preset condition C11, which are not described herein again.
In this embodiment, it is determined, by using a random function, whether at least a part of data in a window Wiz[ki−Az, ki+Bz] meets a preset condition Cz. The implementation manner shown in FIG. 21 is used as an example. According to a rule preset on a deduplication server 103, a window Wi1[ki−169, ki] is determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. As shown in FIG. 32, Wi1 represents the window Wi1[ki−169, ki], and 5 bytes are selected to determine whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 32, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1, a2, a3, a4, and a5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any ar of a1, a2, a3, a4, and a5 meets 0≦ar≦255. a1, a2, a3, a4, and a5 form a 1*5 matrix. 256*5 random numbers are selected from random numbers that follow binomial distribution to form a matrix R that is represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




The matrix R is searched for a corresponding value according to the value of a1 and a column in which a1 is located. For example, if a1=36, and a1 is located in a 1st column, a value corresponding to h36,1 is searched for. The matrix R is searched for a corresponding value according to the value of a2 and a column in which a2 is located. For example, if a2=48, and a2 is located in a 2nd column, a value corresponding to h48,2 is searched for. The matrix R is searched for a corresponding value according to the value of a3 and a column in which a3 is located. For example, if a3=26, and a3 is located in a 3rd column, a value corresponding to h26,3 is searched for. The matrix R is searched for a corresponding value according to the value of a4 and a column in which where a4 is located. For example, if a4=26, and a4 is located in a 4th column, a value corresponding to h26,4 is searched for. The matrix R is searched for a corresponding value according to the value of a5 and a column in which a5 is located. For example, if a5=88, and a5 is located in a 5th column, a value corresponding to h88,5 is searched for. S1=h36,1+h48,2+h26,3+h26,4+h88,5, and because the matrix R follows binomial distribution, S1 also follows binomial distribution. When S1 is an even number, the at least a part of data in Wj1 [ki−169, ki] meets the preset condition C1; when S1 is an odd number, the at least a part of data in Wi1[ki−169, ki] does not meet the preset condition C1. A probability that S1 is an even number is 1⁄2, and C1 represents that S1 that is obtained by means of calculation according to the foregoing manner is an even number. In the embodiment shown in FIG. 21, the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. As shown in FIG. 32, “” represents 1 byte separately selected when it is determined whether at least a part of data in the window Wi2[ki−170, ki−1] meets a preset condition C2. In FIG. 32, selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1, b2, b3, b4, and b5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any br of b1, b2, b3, b4, and b5 meets 0≦br≦255. b1, b2, b3, b4 and b5 form a 1*5 matrix. In this implementation manner, manners of determining whether at least a part of data in W1 and Wij2 meets a preset condition are the same, and therefore the matrix R is still used. The matrix R is searched for a corresponding value according to the value of b1 and a column in which b1 is located. For example, if b1=66, and b1 is located in a 1st column, a value corresponding to h66,1 is searched for. The matrix R is searched for a corresponding value according to the value of b2 and a column in which b2 is located. For example, if b2=48, and b2 is located in a 2nd column, a value corresponding to h48,2 is searched for. The matrix R is searched for a corresponding value according to the value of b3 and a column in which b3 is located. For example, if b3=99, and b3 is located in a 3rd column, a value corresponding to h99,3 is searched for. The matrix R is searched for a corresponding value according to the value of b4 and a column in which b4 is located. For example, if b4=26, and b4 is located in a 4th column, a value corresponding to h26,4 is searched for. The matrix R is searched for a corresponding value according to the value of b5 and a column in which b5 is located. For example, if b5=90, and b5 is located in a 5th column, a value corresponding to h90,5 is searched for. S2=h66,1+h48,2+h99,3+h26,4+h90,5, and because the matrix R follows binomial distribution, S2 also follows binomial distribution. When S2 is an even number, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2; when S2 is an odd number, the at least a part of data in Wi2[ki−170, ki−1] does not meet the preset condition C2. A probability that S2 is an even number is 1⁄2. In the embodiment shown in FIG. 21, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2. By using the same rule, separately, it is determined whether at least a part of data in Wi3[ki−171, ki−2] meets a preset condition C3, it is determined whether at least a part of data in Wi4[ki−172, ki−3] meets a preset condition C4, it is determined whether at least a part of data in Wi5[ki−173, ki−4] meets a preset condition C5, it is determined whether at least a part of data in Wi6[ki−174, ki−5] meets a preset condition C6, it is determined whether at least a part of data in Wi7[ki−175, ki−6] meets a preset condition C7, it is determined whether at least a part of data in Wi8[ki−176, ki−7] meets a preset condition C8, it is determined whether at least a part of data in Wi9[ki−177, ki−8] meets a preset condition C9, it is determined whether at least a part of data in Wi10[ki−178, ki−9] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[ki−179, ki−10] meets a preset condition C11. In the implementation manner shown in FIG. 21, the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 7 bytes are skipped from the potential dividing point ki along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of a 7th byte. As shown in FIG. 22, according to the rule preset on the deduplication server 103, a window Wj1[kj−169, kj] is determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[kj−169, kj] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 33, Wj1, represents the window Wj1[kj−169, kj], and it is determined whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 33, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1′, a2′, a3′, a4′, and a5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any ar′ of a1′, a2′, a3′, a4′, and a5′ meets 0≦ar′≦255. a1′, a2′, a3′, a4′, and a5′ form a 1*5 matrix. The manner of determining whether at least a part of data in the window Wj1[kj−169, kj] meets the preset condition C1 is the same as the manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, the matrix R is still used, and is represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




The matrix R is searched for a corresponding value according to the value of a1′ and a column in which a1′ is located. For example, if a1′=16, and a1′ is located in a 1st column, a value corresponding to h16,1 is searched for. The matrix R is searched for a corresponding value according to the value of a2′ and a column in which a2′ is located. For example, if a2′=98, and a2′ is located in a 2nd column, a value corresponding to h98,2 is searched for. The matrix R is searched for a corresponding value according to the value of a3′ and a column in which a3′ is located. For example, if a3′=56, and a3′ is located in a 3rd column, a value corresponding to h56,3 is searched for. The matrix R is searched for a corresponding value according to the value of a4′ and a column in which a4′ is located. For example, if a4′=36, and a4′ is located in a 4th column, a value corresponding to h36,4 is searched for. The matrix R is searched for a corresponding value according to the value of a5′ and a column in which a5′ is located. For example, if a5′=99, and a5′ is located in a 5th column, a value corresponding to h99,5 is searched for. S1′=h16,1+h98,2+h56,3+h36,4+h99,5, and because the matrix R follows binomial distribution, S1′ also follows binomial distribution. When S1′ is an even number, the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1; when S1′ is an odd number, the at least a part of data in Wj1[kj−169, kj] does not meet the preset condition C1. A probability that S1′ is an even number is 1⁄2.
A manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2 [kj2−170, kj−1] meets the preset condition C2. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2, [kj−170, kj−1] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. Selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1′, b2′, b3′, b4′, and b5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any br′ of b1′, b2′, b3′, b4′, and b5′ meets 0≦br′≦255. b1′, b2′, b3′, b4′, and b5′ form a 1*5 matrix. The matrix R the same as that used when it is determined whether the at least a part of data in the window Wi2[ki−170, ki−1] meets the preset condition C2 is used. The matrix R is searched for a corresponding value according to the value of b1′ and a column in which b1′ is located. For example, if b1′=210, and b1′ is located in a 1st column, a value corresponding to h210,1 is searched for. The matrix R is searched for a corresponding value according to the value of b2′ and a column in which b2′ is located. For example, if b2′=156, and b2′ is located in a 2nd column, a value corresponding to h156,2 is searched for. The matrix R is searched for a corresponding value according to the value of b3′ and a column in which b3′ is located. For example, if b3′=144, and b3′ is located in a 3rd column, a value corresponding to h144,3 is searched for. The matrix R is searched for a corresponding value according to the value of b4′ and a column in which b4′ is located. For example, if b4′=60, and b4′ is located in a 4th column, a value corresponding to h60,4 is searched for. The matrix R is searched for a corresponding value according to the value of b5′ and a column in which b5′ is located. For example, if b5′=90, and b5′ is located in a 5th column, a value corresponding to h90,5 is searched for. S2′=h210,1+h156,2+h144,3+h60,4+h90,5. The same as the determining condition of S2, when S2′ is an even number, the at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2, and when S2′ is an odd number, the at least a part of data in Wj2[kj−170, kj−1] does not meet the preset condition C2. A probability that S2′ is an even number is 1⁄2.
Similarly, a manner of determining whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj−10] meets the preset condition C11, which are not described herein again.
In this embodiment, it is determined, by using a random function, whether at least a part of data in a window Wiz[piz−Az, piz+Bz] meets a preset condition Cz. The implementation manner shown in FIG. 21 is used as an example. According to a rule preset on a deduplication server 103, a window Wi1[ki−169, ki] is determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[ki−169, ki] meets a preset condition C1. As shown in FIG. 32, Wi1 represent the window Wi1[ki−169, ki], and 5 bytes are selected to determine whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 32, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1, a2, a3, a4, and a5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any as of a1, a2, a3, a4, and a5 meets 0≦as≦255. a1, a2, a3, a4 and a5 form a 1*5 matrix. 256*5 random numbers are selected from random numbers that follow binomial distribution to form a matrix R that is represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




256*5 random numbers are selected from random numbers that follow binomial distribution to form a matrix G that is represented as:





  
    (
    
      
        
          
            g
            
              0
              ,
              1
            
          
        
        
          
            g
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              0
              ,
              5
            
          
        
      
      
        
          
            g
            
              1
              ,
              1
            
          
        
        
          
            g
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            g
            
              255
              ,
              5
            
          
        
        
          
            g
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            g
            
              255
              ,
              5
            
          
        
      
    
    )
  
  .




According to the value of a1 and a column in which a1 is located, for example, a1=36, and a1 is located in a 1st column, the matrix R is searched for a value corresponding to h36,1, and the matrix G is searched for a value corresponding to g36,1. According to the value of a2 and a column in which a2 is located, for example, a2=48, and a2 is located in a 2nd column, the matrix R is searched for a value corresponding to h48,2, and the matrix G is searched for a value corresponding to g48,2. According to the value of a3 and a column in which a3 is located, for example, a3=26, and a3 is located in a 3rd column, the matrix R is searched for a value corresponding to h26,3, and the matrix G is searched for a value corresponding to g26,3. According to the value of a4 and a column in which a4 is located, for example, a4=26, and a4 is located in a 4th column, the matrix R is searched for a value corresponding to h26,4, and the matrix G is searched for a value corresponding to g26,4. According to the value of a5 and a column in which a5 is located, for example, a5=88, and a5 is located in a 5th column, the matrix R is searched for a value corresponding to h88,5, and the matrix G is searched for a value corresponding to g88,5. S1h=h36,1+h48,2+h26,3+h26,4+h88,5, and because the matrix R follows binomial distribution, S1h also follows binomial distribution. S1g=g36,1+g48,2+g26,4+g26,4+g88,5, and because the matrix G follows binomial distribution, S1g also follows binomial distribution. When one of S1h and S1g is an even number, the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1; when both S1h and S1g are odd numbers, the at least a part of data in Wi1[ki−169, ki] does not meet the preset condition C1, and C1 indicates that one of S1h and S1g obtained according to the foregoing method is an even number. Because both S1h and S1g follow binomial distribution, a probability that S1h is an even number is 1⁄2, a probability that S1g is an even number is 1⁄2, and a probability that one of S1h and S1g is an even number is 1−1⁄4=3⁄4. Therefore, a probability that the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1 is 3⁄4. In the embodiment shown in FIG. 21, the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In the implementation manner shown in FIG. 21, for Wi1[ki−169, ki], Wi2[ki−170, ki−1], Wi3[ki−171, ki−2], Wi4[ki−172, ki−3], Wi5[ki−173, ki−4], Wi6[ki−174, ki−5], Wi7[ki−175, ki−6], Wi8[ki−176, ki−7], Wi9[ki−177, ki−8], Wi10[ki−178, ki−9], and Wi11[ki−179, ki−10], the windows are the same in size, that is, all the windows have a size of 169 bytes, and meanwhile manners of determining whether at least a part of data in a window meets a preset condition are also the same. For details, refer to the foregoing description of determining whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 32, “” represents 1 byte separately selected when it is determined whether at least a part of data in the window Wi2[ki−170, ki−1] meets a preset condition C2. In FIG. 32, selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1, b2, b3, b4, and b5 respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any bs of b1, b2, b3, b4 and b5 meets 0≦bs≦255. b1, b2, b3, b4, and b5 form a 1*5 matrix. In this implementation manner, manners of determining whether at least a part of data in each window meets a preset condition are the same, and therefore the same matrices R and G are still used. According to the value of b1 and a column in which b1 is located, for example, b1=66, and b1 is located in a 1st column, the matrix R is searched for a value corresponding to h66,1, and the matrix G is searched for a value corresponding to g66,1. According to the value of b2 and a column in which b2 is located, for example, b2=48, and b2 is located in a 2nd column, the matrix R is searched for a value corresponding to h48,2, and the matrix G is searched for a value corresponding to g48,2. According to the value of b3 and a column in which b3 is located, for example, b3=99, and b3 is located in a 3rd column, the matrix R is searched for a value corresponding to h99,3, and the matrix G is searched for a value corresponding to g99,3. According to the value of b4 and a column in which b4 is located, for example, b4=26, and b4 is located in a 4th column, the matrix R is searched for a value corresponding to h26,4, and the matrix G is searched for a value corresponding to g26,4. According to the value of b5 and a column in which b5 is located, for example, b5=90, and b5 is located in a 5th column, the matrix R is searched for a value corresponding to h90,5, and the matrix G is searched for a value corresponding to g90,5. S2h=h66,1+h48,2+h99,3+h26,4+h90,5, and because the matrix R follows binomial distribution, S2h also follows binomial distribution. S2g=g66,1+g48,2+g99,3+g26,4+g90,5, and because the matrix G follows binomial distribution, S2g also follows binomial distribution. When one of S2h and S2g is an even number, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2; when both S2h and S2g are odd numbers, the at least a part of data in Wi2[ki−170, ki−1] does not meet the preset condition C2. A probability that one of S2h and S2g is an even number is 3⁄4. In the embodiment shown in FIG. 21, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2. By using the same rule, separately, it is determined whether at least a part of data in Wi3[ki−171, ki−2] meets a preset condition C3, it is determined whether at least a part of data in Wi4[ki−172, ki−3] meets a preset condition C4, it is determined whether at least a part of data in Wi5[ki−173, ki−4] meets a preset condition C5, it is determined whether at least a part of data in Wi6[ki−174, ki−5] meets a preset condition C6, it is determined whether at least a part of data in Wi7[ki−175, ki−6] meets a preset condition C7, it is determined whether at least a part of data in Wi8[ki−176, ki−7] meets a preset condition C8, it is determined whether at least a part of data in Wi9[ki−177, ki−8] meets a preset condition C9, it is determined whether at least a part of data in Wi10[ki−178, ki−9] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[ki−179, ki−10] meets a preset condition C11. In the implementation manner shown in FIG. 21, the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 7 bytes are skipped from the potential dividing point ki along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of a 7th byte. As shown in FIG. 22, according to the rule preset on the deduplication server 103, a window Wj1[kj−169, kj] is determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[kj−169, kj] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 33, Wj1 represents the window Wj1[kj−169, kj], and it is determined whether the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1. In FIG. 33, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are converted into decimal values that are represented as a1′, a2′, a3′, a4′, and a5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any as′ of a1′, a2′, a3′, a4′, and a5′ meets 0≦as′≦255. a1′, a2′, a3′, a4′ and a5′ form a 1*5 matrix. The matrices R and G the same as those used when it is determined whether the at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1 are used, and are represented as:




  
    (
    
      
        
          
            h
            
              0
              ,
              1
            
          
        
        
          
            h
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              0
              ,
              5
            
          
        
      
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              255
              ,
              5
            
          
        
        
          
            h
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            h
            
              255
              ,
              5
            
          
        
      
    
    )
  
  ⁢
  
    
  
  ⁢
  and
  ⁢
  
    
  
  ⁢
  
    (
    
      
        
          
            g
            
              0
              ,
              1
            
          
        
        
          
            g
            
              0
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              0
              ,
              5
            
          
        
      
      
        
          
            g
            
              1
              ,
              1
            
          
        
        
          
            g
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            g
            
              1
              ,
              5
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            g
            
              255
              ,
              5
            
          
        
        
          
            g
            
              255
              ,
              5
            
          
        
        
          ...
        
        
          
            g
            
              255
              ,
              5
            
          
        
      
    
    )
  




respectively.

According to the value of a1′ and a column in which a1′ is located, for example, a1′=16, and a1′ is located in a 1st column, the matrix R is searched for a value corresponding to h16,1, and the matrix G is searched for a value corresponding to g16,1. According to the value of a2′ and a column in which a2′ is located, for example, a2′=98, and a2′ is located in a 2nd column, the matrix R is searched for a value corresponding to h98,2, and the matrix G is searched for a value corresponding to g98,2. According to the value of a3′ and a column in which a3′ is located, for example, a3′=56, and a3′ is located in a 3rd column, the matrix R is searched for a value corresponding to h56,3, and the matrix G is searched for a value corresponding to g56,3. According to the value of a4′ and a column in which a4′ is located, for example, a4′=36, and a4′ is located in a 4th column, the matrix R is searched for a value corresponding to h36,4, and the matrix G is searched for a value corresponding to g36,4. According to the value of a5′ and a column in which a5′ is located, for example, a5′=99, and a5′ is located in a 5th column, the matrix R is searched for a value corresponding to h99,5, and the matrix G is searched for a value corresponding to g99,5. S1h′=h16,1+h98,2+h56,3+h36,4+h99,5, and because the matrix R follows binomial distribution, S1h′ also follows binomial distribution. S1g′=g16,1+g98,2+g56,3+g36,4+g99,5, and because the matrix G follows binomial distribution, S1g′ also follows binomial distribution. When one of S1h′ and S1g′ is an even number, the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1; when both S1h′ and S1g′ are odd numbers, the at least a part of data in Wj1[kj−169, kj] does not meet the preset condition C1. A probability that one of S1h′ and S1g′ is an even number is 3⁄4.
A manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[kj−170, kj−1] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. In FIG. 33, selected bytes are represented as sequence numbers 170, 128, 86, 44 and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are converted into decimal values that are represented as b1′, b2′, b3′, b4′, and b5′ respectively. Because 1 byte is formed by 8 bits, each byte “” serves as a value, and any bs′ of b1′, b2′, b3′, b4′, and b5′ meets 0≦bs′≦255. b1′, b2′, b3′, b4′, and b5′ form a 1*5 matrix. The matrices R and G the same as those used when it is determined whether the at least a part of data in the window Wi2[ki−170, ki−1] meets the preset condition C2 are used. According to the value of b1′ and a column in which b1′ is located, for example, b1′=210, and b1′ is located in a 1st column, the matrix R is searched for a value corresponding to h210,1, and the matrix G is searched for a value corresponding to g210,1. According to the value of b2′ and a column in which b2′ is located, for example, b2′=156, and b2′ is located in a 2nd column, the matrix R is searched for a value corresponding to h156,2, and the matrix G is searched for a value corresponding to g156,2. According to the value of b3′ and a column in which b3′ is located, for example, b3′=144, and b3′ is located in a 3rd column, the matrix R is searched for a value corresponding to h144,3, and the matrix G is searched for a value corresponding to g144,3. According to the value of b4′ and a column in which b4′ is located, for example, b4′=60, and b4′ is located in a 4th column, the matrix R is searched for a value corresponding to h60,4, and the matrix G is searched for a value corresponding to g60,4. According to the value of b5′ and a column in which b5′ is located, for example, b5′=90, and b5′ is located in a 5th column, the matrix R is searched for a value corresponding to h90,5, and the matrix G is searched for a value corresponding to g90,5. S2h′=h210,1+h156,2+h144,3+h60,4+h90,5, and S2g′=g210,1+g156,2+g144,3+g60,4+g90,5. When one of S2h′ and S2g′ is an even number, the at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2; when both S2h′ and S2g′ are odd numbers, the at least a part of data in Wj2[kj−170, kj−1] does not meet the preset condition C2. A probability that one of S2h′ and S2g′ is an even number is 3⁄4.
Similarly, a manner of determining whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[ki−171, kj−2] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets the preset condition C10, and it is determined whether at least a part of data in Wj11 [kj−179, kj−10] meets the preset condition C11, which are not described herein again.
In this embodiment, it is determined, by using a random function, whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz. The implementation manner shown in FIG. 21 is used as an example. According to a rule preset on a deduplication server 103, a window Wi1[ki−169, ki] is determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[ki−169, ki] meets a preset condition C1. As shown in FIG. 32, Wi1 represents the window Wi1[ki−169, ki], and 5 bytes are selected to determine whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 32, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are regarded as 40 sequential bits, which are represented as a1, a2, a3, a4, . . . , and a40 separately. For any at of a1, a2, a3, a4, . . . , and a40, when at=0, Vat=−1, and when at=1, Vat=1. According to a correspondence between at and Vat, Va1, Va2, Va3, Va4, . . . , and Va40 are generated. 40 random numbers are selected from random numbers that follow normal distribution, and are represented as: h1, h2, h3, h4, . . . , and h40 separately. Sa=Va1*h1+Va2*h2+Va3*h3+Va4*h4+ . . . +Va40*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sa also follows normal distribution. When Sa is a positive number, the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1; when Sa is a negative number or 0, the at least a part of data in Wi1[ki−169, ki] does not meet the preset condition C1. A probability that Sa is a positive number is 1⁄2. In the embodiment shown in FIG. 21, the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. As shown in FIG. 32, “” represents 1 byte separately selected when it is determined whether at least a part of data in a window Wi2[ki−170, ki−1] meets a preset condition C2. In FIG. 32, selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are regarded as 40 sequential bits, which are represented as b1, b2, b3, b4, . . . , and b40 separately. For any bt of b1, b2, b3, b4, . . . , and b40, when bt=0, Vbt=−1, and when bt=1, Vbt=1. According to a correspondence between bt and Vbt, Vb1, Vb2, Vb3, Vb4, . . . , and Vb40 are generated. A manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi2[ki−170, ki−1] meets the preset condition C2. Therefore, the same random numbers are used: h1, h2, h3, h4, . . . , and h40, and Sb=Vb1*h1+Vb2*h2+Vb3*h3+Vb4*h4+ . . . +Vb40*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sb also follows normal distribution. When Sb is a positive number, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2; when Sb is a negative number or 0, the at least a part of data in Wi2[ki−170, ki−1] does not meet the preset condition C2. A probability that Sb is a positive number is 1⁄2. In the embodiment shown in FIG. 21, the at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2. By using the same rule, separately it is determined whether at least a part of data in Wi3[ki−171, ki−2] meets a preset condition C3, it is determined whether at least a part of data in Wi4[ki−172, ki−3] meets a preset condition C4, it is determined whether at least a part of data in Wi5[ki−173, ki−4] meets a preset condition C5, it is determined whether at least a part of data in Wi6[ki−174, ki−5] meets a preset condition C6, it is determined whether at least a part of data in Wi7[ki−175, ki−6] meets a preset condition C7, it is determined whether at least a part of data in Wi8[kj−176, ki−7] meets a preset condition C8, it is determined whether at least a part of data in Wi9[ki−177, kj−8] meets a preset condition C9, it is determined whether at least a part of data in Wi10[ki−178, ki−9] meets a preset condition C10, and it is determined whether at least a part of data in Wi11[kj−179, ki−10] meets a preset condition C11. In the implementation manner shown in FIG. 21, the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 7 bytes are skipped from the potential dividing point ki along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of a 7th byte. As shown in FIG. 22, according to the rule preset on the deduplication server 103, a window Wj1[kj−169, kj] is determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj, [kj−169, kj] meets the preset condition C1 is the same as the manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, as shown in FIG. 33, Wj1 represents the window Wj1[kj−169, kj], and 5 bytes are selected to determine whether at least a part of data in Wj1[kj−169, kj] meets the preset condition C1. In FIG. 33, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 in FIG. 33 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 are regarded as 40 sequential bits, which are represented as a1′, a2′, a3′, a4′, . . . , and a40′ separately. For any at′ of a1′, a2′, a3′, a4′, . . . , and a40′, when at′=0, Vat′=−1, and when at′=1, Vat′=1. According to a correspondence between at′ and Vat′, Va1′, Va2′, Va3′, Va4′, . . . , and Va40′ are generated. The manner of determining whether at least a part of data in the window Wj1[kj−169, kj] meets the preset condition C1 is the same as the manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, the same random numbers are used: h1, h2, h3, h4, . . . , and h40. Sa′=Va1′*h1+Va2′*h2+Va3′*h3+Va4′*h4+ . . . +Va40′*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sa′ also follows normal distribution. When Sa′ is a positive number, the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1; when Sa′ is a negative number or 0, the at least a part of data in Wj1[kj−169, kj] does not meet the preset condition C1. A probability that Sa′ is a positive number is 1⁄2.
The manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2. Therefore, as shown in FIG. 33, “” represents 1 byte selected when it is determined whether the at least a part of data in the window Wj2[kj−170, kj−1] meets the preset condition C2, and there are 42 bytes between two adjacent selected bytes. In FIG. 33, selected bytes are represented as sequence numbers 170, 128, 86, 44, and 2 separately, and there are 42 bytes between two adjacent selected bytes. The bytes “” whose sequence numbers are 170, 128, 86, 44, and 2 are regarded as 40 sequential bits, which are represented as b1′, b2′, b3′, b4′, . . . , and b40′ separately. For any b1′ of b1′, b2′, b3′, b4′, . . . , and b40′, when bt′=0, Vbt′=−1, and when bt′=1, Vbt′=1. According to a correspondence between bt′ and Vbt′, Vb1′, Vb2′, Vb3′, Vb4′, . . . , and Vb40′ are generated. The manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as the manner of determining whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2. Therefore, the same random numbers are used: h1, h2, h3, h4, . . . , and h40, and Sb′=Vb1′*h1+Vb2′*h2+Vb3′*h3+Vb4′*h4+ . . . +Vb40′*h40. Because h1, h2, h3, h4, . . . , and h40 follow normal distribution, Sb′ also follows normal distribution. When Sb′ is a positive number, the at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2; when Sb′ is a negative number or 0, the at least a part of data in Wj2[kj−170, kj−1] does not meet the preset condition C2. A probability that Sb′ is a positive number is 1⁄2.
Similarly, a manner of determining whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj−10] meets the preset condition C11, which are not described herein again.
In this embodiment, it is determined, by using a random function, whether at least a part of data in a window Wiz[ki−Az, ki+Bz] meets a preset condition Cz. The implementation manner shown in FIG. 21 is still used as an example. According to a rule preset on a deduplication server 103, for the potential dividing point ki, a window Wi1[ki−169, ki] is determined for a potential dividing point ki, and it is determined whether at least a part of data in Wi1[ki−169, ki] meets a preset condition C1. As shown in FIG. 32, Wi1 represents the window Wi1[ki−169, ki], and 5 bytes are selected to determine whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. In FIG. 32, each of bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes. Each of the bytes “” whose sequence numbers are 169, 127, 85, 43, and 1 is converted into 1 decimal number, the range of which is 0−(2^40−1). An even distribution random number generator is used to generate 1 designated value for each decimal number in 0−(2^40−1), and a correspondence R between each decimal number in 0−(2^40−1) and the designated value is recorded. Once being designated, a designated value corresponding to a decimal number remains unchanged, and the designated value follows even distribution. If the designated value is an even number, the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1; if the designated value is an odd number, the at least a part of data in Wi1[ki−169, ki] does not meet the preset condition C1. C1 represents that the designated value obtained according to the foregoing method is an even number. Because a probability that a random number in even distribution is an even number is 1⁄2, a probability that the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1 is 1⁄2. In the implementation manner shown in FIG. 21, by using the same rule, separately, it is determined whether at least a part of data in Wi2[ki−170, ki−1] meets a preset condition C2, it is determined whether at least a part of data in Wi3[ki−171, ki−2] meets a preset condition C3, it is determined whether at least a part of data in Wi4[ki−172, ki−3] meets a preset condition C4, it is determined whether at least a part of data in Wi5[ki−173, ki−4] meets a preset condition C5, which are not described herein again.
When the at least a part of data in Wi5[ki−173, ki−4] does not meet the preset condition C5, 7 bytes are skipped from the potential dividing point ki along a direction of searching for a data stream dividing point, and a current potential dividing point kj is obtained at an end position of a 7th byte. As shown in FIG. 22, according to the rule preset on the deduplication server 103, a window Wj1[kj−169, kj] is determined for the potential dividing point kj. A manner of determining whether at least a part of data in the window Wj1[kj−169, kj] meets the preset condition C1 is the same as a manner of determining whether at least a part of data in the window Wi1[ki−169, ki] meets the preset condition C1. Therefore, the same correspondence R between each decimal number in 0−(2^40−1) and a designated value is used. As shown in FIG. 33, Wj1 represents the window, and 5 bytes are selected to determine whether the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1. In FIG. 33, “” represents 1 selected byte, and there are 42 bytes between two adjacent selected bytes “”. Each of bytes “” whose sequence numbers 169, 127, 85, 43, and 1 is converted into 1 decimal number, and R is searched for a designated value corresponding to the decimal number. If the designated value is an even number, the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1; if the designated value is an odd number, the at least a part of data in Wj1[kj−169, kj] does not meet the preset condition C1. Because a probability that a random number in even distribution is an even number is 1⁄2, a probability that the at least a part of data in Wj1[kj−169, kj] meets the preset condition C1 is 1⁄2. Similarly, a manner of determining whether at least a part of data in Wi2[ki−170, ki−1] meets the preset condition C2 is the same as a manner of determining whether at least a part of data in Wj2[kj−170, kj−1] meets the preset condition C2, and a manner of determining whether at least a part of data in Wi3[ki−171, ki−2] meets the preset condition C3 is the same as a manner of determining whether at least a part of data in Wj3[kj−171, kj−2] meets the preset condition C3. Similarly, it is determined whether at least a part of data in Wj4[kj−172, kj−3] meets the preset condition C4, it is determined whether at least a part of data in Wj5[kj−173, kj−4] meets the preset condition C5, it is determined whether at least a part of data in Wj6[kj−174, kj−5] meets the preset condition C6, it is determined whether at least a part of data in Wj7[kj−175, kj−6] meets the preset condition C7, it is determined whether at least a part of data in Wj8[kj−176, kj−7] meets the preset condition C8, it is determined whether at least a part of data in Wj9[kj−177, kj−8] meets the preset condition C9, it is determined whether at least a part of data in Wj10[kj−178, kj−9] meets the preset condition C10, and it is determined whether at least a part of data in Wj11[kj−179, kj−10] meets the preset condition C11, which are not described herein again.
The deduplication server 103 in the embodiment of the present invention shown in FIG. 1 refers to an apparatus that can implement a technical solution described in an embodiment of the present invention, and as shown in FIG. 18, usually includes a central processing unit, a primary memory, and an input/output interface. The central processing unit, the primary memory, and the input/output interface communicate with each other. The main memory stores an executable instruction, and the central processing unit executes the executable instruction stored in the main memory to perform a specific function, so that the deduplication server 103 has a specific function, for example, searching for a data stream dividing point described in FIG. 20 to FIG. 33 in the embodiments of the present invention. Therefore, as shown in FIG. 19, according to the embodiments of the present invention shown in FIG. 20 to FIG. 33, for the deduplication server 103, a rule is preset on the deduplication server 103, where the rule is: for a potential dividing point k, determining M windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers.
The deduplication server 103 includes a determining unit 1901 and a judging and processing unit 1902. The determining unit 1901 is configured to perform step (a):
(a) determining a corresponding window Wiz[ki−Az, ki+Bz] for a current potential dividing point ki according to the rule, where i and z are integers, and 1≦z≦M.
The judging and processing unit 1902 is configured to: determine whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets a preset condition Cz;
when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skip N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along a direction of searching for a data stream dividing point, where N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a new potential dividing point, where the determining unit 1901 performs step (a) for the new potential dividing point; and
when at least a part of data in each window Wix[ki−Ax, ki+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, select the current potential dividing point ki as a data stream dividing point.
Further, the rule further includes that at least two windows Wie[ki−Ae, ki+Be] and Wif[ki−Af, ki+Bf] meet conditions |Ae+Be|=|Af+Bf and Ce=Cf. Further, the rule further includes that Ae and Af are positive integers. Further, the rule further includes Ae−1=Af and Be+1=Bf.
Further, the judging and processing unit 1902 is specifically configured to determine, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz. Still further, the judging and processing unit 1902 specifically determines, by using a hash function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.
Further, the judging and processing unit 1902 is configured to: when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skip the N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and the determining unit 1901 performs step (a) for the new potential dividing point, where according to the rule, a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[ki−Az, ki+Bz] or a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point falls within a range of the window Wiz[ki−Az, ki+Bz], where the window Wic[ki−Ac, ki+Bc] determined for the new potential dividing point is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M windows that are determined for the new potential dividing point according to the rule.
Further, that the judging and processing unit 1902 determines, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz specifically includes:
selecting F bytes in the window Wiz[ki−Az, ki+Bz], and using the F bytes repeatedly H times to obtain F*H bytes in total, where F≧1, each byte is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the F*H bytes, bits corresponding to the F*H bytes may be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




where when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1, where am,n represents any one of am,1, . . . , and am,8, a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the F*H bytes, the matrix Va is represented as:





  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




F*H*8 random numbers are selected from random numbers following normal distribution to form a matrix R, the matrix R is represented as:





  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers in an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8, Sa1, Sa2, . . . , and SaF*H are obtained in a same way, a quantity K of values greater than 0 among Sa1, Sa2, . . . , and SaF*H is counted, and when K is an even number, the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

According to the method for searching for a data stream dividing point based on a server in the embodiments of the present invention shown in FIG. 20 to FIG. 33, a window Wix[ki−Ax, ki+Bx] is determined for a potential dividing point ki, where, x indicates consecutive natural numbers from 1 to M separately, and M≧2. It may be determined in parallel whether at least a part of data in each window of M windows meets a preset condition Cx, or it may be determined sequentially whether at least a part of data in windows meets a preset condition, or it may be first determined that at least a part of data in a window Wi1[pi1−A1, pi1+B1] meets a preset condition C1, then it is determined that at least a part of data in Wi2[pi2−A2, pi2+B2] meets a preset condition C2, until it is determined that at least a part of data in Wim[pim−Am, pim+Bm] meets a preset condition Cm. Other windows in this embodiment are determined in a same manner as the above, which is not described again.
In addition, according to the embodiments of the present invention shown in FIG. 20 to FIG. 33, a rule is preset on the deduplication server 103, where the rule is: determining M windows Wx[k−Ax, k+Bx] for a potential dividing point k and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to M separately, and M≧2. In the preset rule, A1, A2, A3, . . . , and Am may be not all equal, B1, B2, B3, . . . , and Bm may be not all equal, and C1, C2, C3, . . . , and CM may also be not all the same. In the implementation manner shown in FIG. 21, for Wi1[ki−169, ki], Wi2[ki−170, ki−1], Wi3[ki−171, ki−2], Wi4[ki−172, ki−3], Wi5[ki−173, ki−4], Wi6[ki−174, ki−5], Wi7[ki−175, ki−6], Wi8[ki−176, ki−7], Wi9[ki−177, ki−8], Wi10[ki−178, ki−9], and Wi11[ki−179, ki−10], the windows are the same in size, that is, all the windows have a size of 169 bytes, and meanwhile manners of determining whether at least a part of data in a window meets a preset condition are also the same. For details, refer to the foregoing description of determining whether the at least a part of data in Wi1[ki−169, ki] meets the preset condition C1. However, in the implementation manner shown in FIG. 11, the windows Wi1[ki−169, ki], Wi2[ki−170, ki−1], Wi3[ki−171, ki−2], Wi4[ki−172, ki−3], Wi5[ki−173, ki−4], Wi6[ki−174, ki−5], Wi7[ki−175, ki−6], Wi8[ki−176, ki−7], Wi9[ki−177, ki−8], Wi10[ki−168, ki−1], and Wi11[ki−179, ki+3], may be different in size, and meanwhile the manners of determining whether at least a part of data in a window meets a preset condition may also be different. In all embodiments, according to the rule preset on the deduplication server 103, a manner of determining whether at least a part of data in the window Wi1 meets the preset condition C1 is certainly the same as a manner of determining whether at least a part of data in a window Wj1 meets the preset condition C1, a manner of determining whether at least a part of data in Wi2 meets the preset condition C2 is certainly the same as a manner of determining whether at least a part of data in Wj2 meets the preset condition C2, . . . , and a manner of determining whether at least a part of data in a window WiM meets a preset condition CM is certainly the same as a manner of determining whether at least a part of data in a window WjM meets the preset condition CM, which are not described herein again.
According to the embodiments of the present invention shown in FIG. 20 to FIG. 33, the rule is preset on the deduplication server 103, ka, ki, kj, kl, and km are potential dividing points obtained in the search for a dividing point along a direction of searching for a data stream dividing point, and ka, ki, kj, kl, and km all follow the rule. In this embodiment of the present invention, the window Wx[k−Ax, k+Bx] represents a specific range, and data is selected in the specific range to determine whether the data meets the preset condition Cx. Specifically, in the specific range, a part of data may be selected or all data may be selected to determine whether the data meets the preset condition Cx. Reference may be made to the window Wx[k−Ax, k+Bx] for the concept of a window specifically used in this embodiment of the present invention, which is not described herein again.
In the window Wx[k−Ax k+Bx], (k−Ax) and (k+Bx) represent two boundaries of the window Wx[k−Ax, k+Bx], where (k−Ax) represents a boundary, which is in a direction opposite to the direction of searching for a data stream dividing point relative to the potential dividing point k, of the window Wx[k−Ax, k+Bx], and (kj+Bx) represents a boundary, which is in the direction of searching for a data stream dividing point relative to the potential dividing point k, of the window Wx[k−Ax, k+Bx]. Specifically, in the embodiment of the present invention, the direction of searching for a data stream dividing point shown in FIG. 20 to FIG. 33 is from left to right; therefore, (k−Ax) represents a boundary (that is, a left boundary), which is in a direction opposite to the direction of searching for a data stream dividing point relative to the potential dividing point k, of the window Wx[k−Ax, k+Bx], and (k+Bx) represents a boundary (that is, a right boundary), which is in the direction of searching for a data stream dividing point relative to the potential dividing point k, of the window Wx[k−Ax, k+Bx]. If the direction of searching for a data stream dividing point shown in FIG. 20 to FIG. 33 is from right to left, (k−Ax) represents a boundary (that is, a right boundary), which is in a direction opposite to the direction of searching for a data stream dividing point relative to the potential dividing point k, of the window Wx[k−Ax, k+Bx], and (k+Bx) represents a boundary (that is, a left boundary), which is in the direction of searching for a data stream dividing point relative to the potential dividing point k, of the window Wx[k−Ax, k+Bx].
A person of ordinary skill in the art may be aware that, in conjunction with various exemplary units and algorithm steps described in FIG. 20 to FIG. 33 of the embodiments of the present invention, a key feature in the embodiments of the present invention may be combined with other technologies and presented in a more complex form; however, the key feature of the present invention is still included. An alternative dividing point may be used in a real environment. For example, in an implementation manner, according to a rule preset on a deduplication server 103, for a potential dividing point ki, 11 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx] are determined, where x indicates consecutive natural numbers from 1 to 11. When at least a part of data in each window Wx[k−Ax, k+Bx] of the 11 windows meets the preset condition Cx, the potential dividing point ki is a data stream dividing point. When no dividing point is found after a set maximum data chunk is exceeded, a preset rule for the alternative point may be used. The preset rule for the alternative point is similar to the rule preset on the deduplication server 103, and the preset rule for the alternative point is: for example, for a potential dividing point ki, determining 10 windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], where x indicates consecutive natural numbers from 1 to 10. When it is determined that at least a part of data in each window Wx [k−Ax, k+Bx] of the 10 windows meets the preset condition Cx, the potential dividing point ki is a data stream dividing point. When no data stream dividing point is found after a set maximum data chunk is exceeded, an end position of the maximum data chunk serves as a forced dividing point.
According to the embodiments of the present invention shown in FIG. 20 to FIG. 33, a rule is preset on the deduplication server 103, and in the rule, M windows are determined for a potential dividing point k. It is not necessarily required that there be a potential dividing point k in advance, and the potential dividing point k may be determined by using the determined M windows.
A person of ordinary skill in the art may be aware that, in combination with the examples described in the embodiments disclosed in this specification, units and algorithm steps may be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed by hardware or software depends on particular applications and design constraint conditions of the technical solutions.
It may be clearly understood by a person skilled in the art that, for the purpose of convenient and brief description, for a detailed working process of the foregoing system, apparatus, and unit, reference may be made to a corresponding process in the foregoing method embodiments, and details are not described herein again.
In the several provided embodiments, it should be understood that the disclosed system and method may be implemented in other manners. For example, the described apparatus embodiment is merely exemplary. For example, the unit division is merely logical function division and may be other division in actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.
When the functions are implemented in the form of a software functional unit and sold or used as an independent product, the functions may be stored in a computer-readable non-volatile storage medium. Based on such an understanding, the technical solutions of the present invention essentially, or the part contributing to the prior art, or some of the technical solutions may be implemented in a form of a software product. The software product is stored in a non-volatile storage medium, and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some of the steps of the methods described in the embodiments of the present invention. The foregoing non-volatile storage medium includes: any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a magnetic disk, or an optical disc.

## Claims

1. A method performed by a server processor executing computer instructions stored in a server memory for searching for a data stream dividing point for dividing data into a plurality of portions to facilitate data storage according to a rule, wherein the rule comprising: for a potential dividing point k, determining M windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], wherein x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers for establishing a potential dividing point k, the method comprising:
(a) determining a corresponding window Wiz[ki−Az, ki+Bz] for a current potential dividing point ki according to the rule, wherein i and z are integers, and 1≦z≦M;
(b) determining whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets a preset condition Cz; and
when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skipping N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along a direction of searching for a data stream dividing point, wherein N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a new potential dividing point, and performing step (a); and
(c) when at least a part of data in each window Wix[ki−Ax, ki+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, selecting the current potential dividing point ki as a data stream dividing point.

2. The method according to claim 1, wherein the rule further comprises that at least two windows Wie[ki−Ae, ki+Be] and Wif[ki−Af, ki+Bf] meet conditions |Ae+Be|=|Af+Bf| and Ce=Cf.

3. The method according to claim 2, wherein the rule further comprises that Ae and Af are positive integers.

4. The method according to claim 2, wherein the rule further comprises Ae−1=Af and Be+1=Bf.

5. The method according to claim 1, wherein determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

6. The method according to claim 5, wherein the determining, by using a random function, whether the at least a part of data in Wiz[ki−Az, ki+Bz] meets the preset condition Cz is specifically: determining, by using a hash function, whether the at least a part of data in Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

7. The method according to claim 1, wherein when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, the N minimum units U for searching for a data stream dividing point are skipped from the current potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and according to the rule, a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[ki−Az, ki+Bz] or a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point falls within a range of the window Wiz[ki−Az, ki+Bz], wherein the window Wic[ki−Ac, ki+Bc] determined for the new potential dividing point is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M windows that are determined for the new potential dividing point according to the rule.

8. The method according to claim 5, wherein selecting F bytes in the window Wiz[ki−Az, ki+Bz], and using the F bytes repeatedly H times to obtain F*H bytes in total, wherein F≧1, each byte is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the F*H bytes, bits corresponding to the F*H bytes can be represented as:




  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




wherein when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1,wherein am,n represents any one of am,1, . . . , and am,8 a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the F*H bytes, the matrix Va is represented as:




  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




F*H*8 random numbers are selected from random numbers following normal distribution to form a matrix R, the matrix R is represented as:




  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers in an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8, Sa1, Sa2, . . . , and SaF*H are obtained in a same way, a quantity K of values greater than 0 among Sa1, Sa2, . . . , and SaF*H is counted, and when K is an even number, the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

9. A server for searching for a data stream dividing point for dividing data into a plurality of portions to facilitate data storage according to a rule, wherein the rule comprising: for a potential dividing point k, determining M windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], wherein x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers for establishing a potential dividing point k, wherein the server comprises a central processing unit and a primary memory, the central processing unit communicates with the primary memory to execute computer instructions stored therein to perform the steps of:
(a) determining a corresponding window Wiz[ki−Az, ki+Bz] for a current potential dividing point k1 according to the rule, wherein i and z are integers, and 1≦z≦M;
(b) determining whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets a preset condition Cz;
(c) when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skipping N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along a direction of searching for a data stream dividing point, wherein N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a new potential dividing point, and performing step (a); and
(d) when at least a part of data in each window Wix[ki−Ax, ki+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, selecting the current potential dividing point ki as a data stream dividing point.

10. The server according to claim 9, wherein the rule further comprises that at least two windows Wie[ki−Ae, ki+Be] and Wif[ki−Af, ki+Bf] meet conditions |Ae+Be|=|Af+Bf| and Ce=Cf.

11. The server according to claim 10, wherein the rule further comprises that Ae and Af are positive integers.

12. The server according to claim 10, wherein the rule further comprises Ae−1=Af and Be+1=Bf.

13. The server according to claim 9, wherein the central processing unit is specifically configured to determine, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

14. The server according to claim 13, wherein the central processing unit is specifically configured to determine, by using a hash function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

15. The server according to claim 9, wherein when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, the N minimum units U for searching for a data stream dividing point are skipped from the current potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and according to the rule, a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[ki−Az, ki+Bz] or a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point falls within a range of the window Wiz[ki−Az, ki+Bz], wherein the window Wic[ki−Ac, ki+Bc] determined for the new potential dividing point is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M windows that are determined for the new potential dividing point according to the rule.

16. The server according to claim 14, wherein the determining, by the central processing unit by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz specifically comprises:
selecting F bytes in the window Wiz[ki−Az, ki+Bz], and using the F bytes repeatedly H times to obtain F*H bytes in total, wherein F≧1, each byte is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the F*H bytes, bits corresponding to the F*H bytes can be represented as:





  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




wherein when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1, wherein am,n represents any one of am,1, . . . , and am,8, a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the F*H bytes, the matrix Va is represented as:




  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




F*H*8 random numbers are selected from random numbers following normal distribution to form a matrix R, the matrix R is represented as:




  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers in an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8, Sa1, Sa2, . . . , and SaF*H are obtained in a same way, a quantity K of values greater than 0 among Sa1, Sa2, . . . , and SaF*H is counted, and when K is an even number, the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

17. A non-transitory computer-readable storage medium, wherein the computer-readable storage medium is configured to store executable computer instructions for execution by a processor that prompts the processor to determine a potential dividing point k for dividing data into a plurality of portions to facilitate data storage according to a rule, wherein the rule comprising: for a potential dividing point k, determining M windows Wx[k−Ax, k+Bx] and a preset condition Cx corresponding to the window Wx[k−Ax, k+Bx], wherein x indicates consecutive natural numbers from 1 to M, M≧2, and Ax and Bx are integers; and for:
(a) determining a corresponding window Wiz[ki−Az, ki+Bz] for a current potential dividing point ki according to the rule, wherein i and z are integers, and 1≦z≦M;
(b) determining whether at least a part of data in the window Wiz[ki−Az, ki+Bz] meets a preset condition Cz; and
when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, skipping N minimum units U for searching for a data stream dividing point from the current potential dividing point ki along a direction of searching for a data stream dividing point, wherein N*U is not greater than ∥Bz∥+maxx(∥Ax∥), so as to obtain a new potential dividing point, and performing step (a); and
(c) when at least a part of data in each window Wix[ki−Ax, ki+Bx] of M windows of the current potential dividing point ki meets the preset condition Cx, selecting the current potential dividing point ki as a data stream dividing point.

18. The non-transitory computer-readable storage medium according to claim 17, wherein the rule further comprises that at least two windows Wie[ki−Ae, ki+Be] and Wif[ki−Af, ki+Bf] meet conditions |Ae+Be|=|Af+Bf| and Ce=Cf.

19. The non-transitory computer-readable storage medium according to claim 18, wherein the rule further comprises that Ae and Af are positive integers.

20. The non-transitory computer-readable storage medium according to claim 18, wherein the rule further comprises Ae−1=Af and Be+1=Bf.

21. The non-transitory computer-readable storage medium according to claim 17, wherein:
determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

22. The non-transitory computer-readable storage medium according to claim 21, wherein determining, by the server by using a hash function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.

23. The non-transitory computer-readable storage medium according to claim 17, wherein when the at least a part of data in the window Wiz[ki−Az, ki+Bz] does not meet the preset condition Cz, the N minimum units U for searching for a data stream dividing point are skipped from the current potential dividing point ki along the direction of searching for a data stream dividing point, so as to obtain the new potential dividing point, and according to the rule, a left boundary of a window Wic[ki−Ac, ki+Bc] that is determined for the new potential dividing point coincides with a right boundary of the window Wiz[ki−Az, ki+Bz] or a left boundary of a window ic[ki−Ac, ki+Bc] that is determined for the new potential dividing point falls within a range of the window Wiz[ki−Az, ki+Bz], wherein the window Wic[ki−Ac, ki+Bc] determined for the new potential dividing point is a window ranking the first in a sequence, which is obtained according to the direction of searching for a data stream dividing point, of M windows that are determined for the new potential dividing point according to the rule.

24. The non-transitory computer-readable storage medium according to claim 21, wherein the determining, by using a random function, whether the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz specifically comprises:
selecting F bytes in the window Wiz[ki−Az, ki+Bz], and using the F bytes repeatedly H times to obtain F*H bytes in total, wherein F≧1, each byte is formed by 8 bits, which are denoted as am,1, . . . , and am,8, representing the 1st bit to the 8th bit of an mth byte in the F*H bytes, bits corresponding to the F*H bytes can be represented as:





  
    (
    
      
        
          
            a
            
              1
              ,
              1
            
          
        
        
          
            a
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              1
              ,
              8
            
          
        
      
      
        
          
            a
            
              2
              ,
              1
            
          
        
        
          
            a
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            a
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




wherein when am,n=1, Vam,n=1, and when am,n=0, Vam,n=−1, wherein am,n represents any one of am,1, . . . , and am,8, a matrix Va is obtained according to a conversion relationship between am,n and Vam,n from the bits corresponding to the F*H bytes, the matrix Va is represented as:




  
    (
    
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                1
              
              ,
              8
            
          
        
      
      
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              1
            
          
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                a
                ⁢
                
                  
                
                ⁢
                2
              
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            V
            
              
                
                  aF
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




F*H*8 random numbers are selected from random numbers following normal distribution to form a matrix R, the matrix R is represented as:




  
    (
    
      
        
          
            h
            
              1
              ,
              1
            
          
        
        
          
            h
            
              1
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              1
              ,
              8
            
          
        
      
      
        
          
            h
            
              2
              ,
              1
            
          
        
        
          
            h
            
              2
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              2
              ,
              8
            
          
        
      
      
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
        
          ⋮
        
      
      
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              1
            
          
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              2
            
          
        
        
          ...
        
        
          
            h
            
              
                
                  F
                  *
                
                ⁢
                H
              
              ,
              8
            
          
        
      
    
    )
  
  ,




random numbers in an mth row of the matrix Va and an mth row of the matrix R are multiplied and products are added to obtain a value, which is specifically represented as Sam=Vam,1*hm,1+Vam,2*hm,2+ . . . +Vam,8*hm,8, Sa1, Sa2, . . . , and SaF*H are obtained in a same way, a quantity K of values greater than 0 among Sa1, Sa2, . . . , and SaF*H is counted, and when K is an even number, the at least a part of data in the window Wiz[ki−Az, ki+Bz] meets the preset condition Cz.