Abstract:
Information processing system for rapidly performing analysis of semistructured data while preserving fault-tolerance of data for a store request acquiring the number which has been stored of the same and data structures set beforehand, refer to data structure management information to determine a data store unit, instructs replica creation of the data with regard to the data stored in the data store unit in which any of the replicas have been stored, transmits an instruction, for performing a data operation, to a data structure operation unit, whereupon a processing unit, in accordance with the content of an analysis request, performs analysis processing by way of either data stored in any of the data storage units after a data structure operation or data which have not been subject to a data structure operation.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an information processing system and a control method thereof capable of being applied to processing of semi-structured data. 
       BACKGROUND ART 
       [0002]    An amount of data processed by an information processing system has been increased along with a widening field to be processed year by year. Further, types of the data greatly vary from conventional business-use data to actual world information, which is typically a sensor technique. Furthermore, in recent years, it has been vigorously attempted to acquire new knowledge for business and society from log data that has been considered as having less values by analyzing the log data generated in a processing process of the information processing system. A great amount of data including the log data is referred to as “big data” and, as a foundation for realizing great-amount data processing, data processing at high speed for the information processing system is demanded more than ever before. 
         [0003]    Roughly two types of methods are provided for speeding up the information processing system. One of them is a method for improving performance of a stand-alone computer referred to as “scale up”. Another one is referred to as “scale out” and, by arranging a plurality of computers, the performance of the information processing system is improved. Recently, the performance of the computer by the scale up has been less improved than before, and the performance thereof by the scale out has become a main stream. Furthermore, in distributed processing of a scale-out type, a plurality of computers including commodity hardware are arranged to realize the distributed processing at a moderate cost, and also a distributed processing foundation which a user can conveniently use is provided for the information processing system. 
         [0004]    As described above, since it is assumed that the commodity hardware is used, the distributed processing foundation used in recent years realizes a scale-out property of the distributed processing by dispersing and arranging a file to be processed in each computer to perform the distributed processing at a high speed. 
         [0005]    Further, to perform the distributed processing foundation at a high speed, a dedicated file system is prepared. Since it is assumed that the commodity hardware is used in the file system, by redundantly retaining the file to be processed in the plurality of computers, fault tolerance of the file can be realized. 
         [0006]    Furthermore, since the great-amount data processing has become more popular, compared with the conventional processing, a storage structure of the data has been changing. So far, the data to be processed has been generally stored in a relational database. Such data is referred to as “structured data”. When the relational database is used, it is appropriate for the processing for searching and extracting the data. However, a great number of hours and loading works on the database are necessary to perform the search and the extraction. 
         [0007]    On the other hand, in the great amount of data processing, since the amount and types of the data have been increased, the conventional relational database cannot solve problems. First, the data that cannot be treated by the conventional structured data, such as images and audio, is going to be a processing target. Such data is difficult to be processed by the conventional relational database. Although such data is structured like the log data, since the great amount and types of data in a file format exists, it is not realistic to load the data into the relational database. 
         [0008]    From the above-described problems, in the distributed processing foundation in recent years, the method has become the main stream for performing the distributed processing on the data in an original file format without loading the data to be processed into the relational database. Since structuring the data such as the images and the audio is difficult, they are generally referred to as non-structured data. Further, the data that is structured like the log data but exists as the file format is referred to as semi-structured data. The semi-structured data includes a comma separated values (CSV) file and an eXtended marked-up language (XML) file. 
         [0009]    Since the semi-structured data including the CSV file is not structured but stored in the file format, data access to the semi-structured data depends on the data structure of the semi-structured data. A case where a depending relationship causes a problem will be described below according to examples. 
         [0010]    An example of the CSV file will be described herein. When the CSV file is sequentially read from a disk, the data on the CSV file is sequentially accessed in a row direction. In a case of the CSV file, one row generally stores information related to a time stamp, a name for discriminating each record, and attribute values of various types as one record. Therefore, when the CSV file is sequentially read, the data for each record can be sequentially read. 
         [0011]    On the other hand, when analysis is performed using the information stored in the CSV file, processing is generally, widely performed in which the attribute values of the same type are extracted and the extracted attribute values are added up. In such processing, when the attribute values of the same type are extracted and added up, access in the row direction of the CSV file occurs. Therefore, the CSV file is simply stored in the disk and the access in the row direction of the CSV file becomes random access on the disk and, thus, an access speed in the row direction is slowed down. 
         [0012]    As to the problem described above, as a conventional solution method, a method is provided for using columnstore in a format capable of processing the data stored in the database in the row direction, Products using this method includes Google BigTable (trademark) indicated in non-patent literature (NPL) 1. Further, the patent literature disclosing a similar technique includes patent literature (PTL) 1. 
         [0013]    In the method using the columnstore, when input data such as the structured data and the semi-structured data is loaded into the information processing system, the input data is stored in the columnstore to be converted into the data having the data structure appropriate for the row direction access. More specifically, the data is stored with the row and the column of the data previously replaced with each other so that the access in the row direction becomes the sequential access. 
       CITATION LIST 
     Patent Literature 
       [0014]    PTL 1: Japanese Patent Application Laid-Open Publication No. H11-154155 
       Non-Patent Literature 
       [0015]    NPL 1: F. Chang et al., “Bigtable: A distributed storage system for structured data”, In Proc. OSDI, 2006, pp 205-218. 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0016]    The distributed processing foundation used in recent years needs analysis of the semi-structured data. When the analysis is needed, and when the method using the columnstore indicated in the NPL 1 and the PTL 1 is adopted, problems occur as follows. 
         [0017]    In the information processing system using the distributed processing foundation, when the columnstore is used, extra data by an amount of the data newly stored in the columnstore needs to be included in the information processing system. On the other hand, the information processing system using the distributed processing foundation stores the redundant data to improve fault tolerance of the data. Due to the two points described above, when the information processing system using the distributed processing foundation adopts the columnstore, the extra data needs to be provided. 
       Solution to Problem 
       [0018]    To solve the problems described above, according to one aspect of the present invention, an information processing system performing storage of data and analysis of the stored data in response to a request from an external apparatus, the information processing system includes: 
         [0019]    a plurality of data storage units each configured to provide a storage area of the data; 
         [0020]    a plurality of data structure operation units each associated with the each data storage unit and configured to perform a predetermined operation on a data structure of the data stored in the data storage unit; 
         [0021]    a plurality of data redundancy units each associated with the each data storage unit and configured to transmit any of the data stored in the data storage unit to the other data storage unit; 
         [0022]    a data placement determination unit configured to determine in which of a plurality of the data storage units the data requested from the external apparatus is to be stored; 
         [0023]    a data redundancy determination unit configured to cause a plurality of the data redundancy units to transmit any of the data to the other data storage unit; 
         [0024]    a data structure operation determination unit configured to cause the each data structure operation unit to operate the data structure of the data stored in the data storage unit; 
         [0025]    a data structure management information retaining unit configured to retain data structure management data that is information about the data to be stored in the plurality of the data storage units and the data structure of the data; and 
         [0026]    an analysis processing unit configured to receive an analysis request on the data stored in the data storage unit from the external apparatus and perform analysis processing on the data according to the analysis request, 
         [0027]    wherein the data placement determination unit acquires, on the data for which storage request has been received from the external apparatus, the number of pieces of data stored in the information processing system and the data structure of the data to be stored that are previously set, determines the data storage unit in which the data according to the storage request is to be stored, with reference to the data structure management information about corresponding data stored in the data structure management information retaining unit, and then notifies the external apparatus, 
         [0028]    wherein the data redundancy determination unit instructs the data redundancy unit to create a replica of the data according to the storage request with reference to the data structure management information retaining unit and perform transmission to the data storage unit that is a storage destination of the created replica, 
         [0029]    wherein the data structure operation determination unit transmits to the data structure operation unit an instruction for performing a data operation on the data stored in any of the data storage units in which the replica is stored with reference to the data structure management information recorded in the data structure management information retaining unit, and 
         [0030]    wherein the analysis processing unit performs the analysis processing based on either of the data after the data structure operation and the data of unoperated data structure, both of the data being stored in any of the data storage units depending on a content of the analysis request. 
         [0031]    Further, another embodiment of the present invention is a control method of the information processing system. 
       Advantageous Effects of Invention 
       [0032]    According to the present invention, the information processing system and the control method thereof can be provided that can perform the analysis of the semi-structured data at a high speed without including the extra data in the information processing system while maintaining the fault tolerance of the data. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0033]      FIG. 1  illustrates a configuration example of an information processing system  10  according to a first embodiment. 
           [0034]      FIG. 2  illustrates a configuration example of a computer definition file  40 . 
           [0035]      FIG. 3  illustrates a configuration example of a policy definition file  50 . 
           [0036]      FIG. 4  illustrates a configuration example of an analysis request setting screen  61 . 
           [0037]      FIG. 5  illustrates a configuration example of a data structure management table  70 . 
           [0038]      FIG. 6  is a schematic diagram illustrating a data conversion processing example according to the present embodiment. 
           [0039]      FIG. 7  is an example of a sequence diagram illustrating processing when a file is copied to the information processing system  10 . 
           [0040]      FIG. 8  is a flowchart illustrating a processing example of a data placement determination unit  100 . 
           [0041]      FIG. 9  is a flowchart illustrating a processing example of a data redundancy determination unit  200 . 
           [0042]      FIG. 10  is a flowchart illustrating a processing example of a data structure conversion determination unit  300 . 
           [0043]      FIG. 11  is a flowchart illustrating a processing example of a data structure conversion unit  1200 . 
           [0044]      FIG. 12  is a flowchart illustrating a processing example of a data structure reverse-conversion unit  1300 . 
           [0045]      FIG. 13  is a sequence diagram illustrating a processing example when an analysis request is received according to the first embodiment. 
           [0046]      FIG. 14  is a flowchart illustrating a processing example of an analysis execution location determination unit  500 . 
           [0047]      FIG. 15  is a sequence diagram illustrating a processing example when a failure occurs with a processing computer  21 . 
           [0048]      FIG. 16  is a flowchart illustrating a processing example of a data recovery determination unit  600 . 
           [0049]      FIG. 17  is a configuration example of an information processing system  10  according to a second embodiment. 
           [0050]      FIG. 18  is a configuration example of a data structure/statistics information management table  70 A. 
           [0051]      FIG. 19  is a sequential diagram illustrating a processing example when an analysis request is received according to a second embodiment. 
           [0052]      FIG. 20  is a flowchart illustrating a processing example of a statistics information recording unit  700 . 
           [0053]      FIG. 21  is a sequential diagram illustrating a processing example when a retention ratio is changed according to the second embodiment. 
           [0054]      FIG. 22  is a flowchart illustrating a processing example of a retention ratio change determination unit  800 . 
           [0055]      FIG. 23  is a configuration example of the information processing system  10  according to a third embodiment. 
           [0056]      FIG. 24  is a configuration example of a conversion rule definition file  90 . 
           [0057]      FIG. 25  is a sequential diagram illustrating a processing example when a retention ratio is changed according to the third embodiment. 
           [0058]      FIG. 26  is a flowchart illustrating a processing example of a load information notification unit  1500 . 
           [0059]      FIG. 27  is a flowchart illustrating a processing example of a retention ratio change determination unit  800  according to the third embodiment. 
           [0060]      FIG. 28  is a flowchart illustrating a processing example of a data structure conversion method determination unit  900 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0061]    With reference to figures, embodiments for implementing the present invention will be described below. 
       Example 1 
       [0062]      FIG. 1  illustrates an entire configuration of an information processing system  10  according to a first embodiment. 
         [0063]    A hardware configuration example of an information processing system  10  according to the first embodiment of the present invention will be described. The information processing system  10  includes a management computer  20  and processing computers  1  to  3  ( 21 - 1  to  21 - 3 ). In  FIG. 1  illustrating an example of the present embodiment, the information processing system  10  includes three processing computers, but may include four or more. Further, according to an example illustrated in  FIG. 1 , one management computer  20  is provided, but, depending on a redundancy structure, a plurality of management computers  20  may be operated. The management computer  20  and the processing computer  30  each include central processing devices  30 - 0  to  30 - 3 , main storage devices  31 - 0  to  31 - 3 , secondary storage devices  32 - 0  to  32 - 3 , network interfaces  33 - 0  to  33 - 3 , input devices  34 - 0  to  34 - 3 , output devices  35 - 0  to  35 - 3  therein, and their elements are mutually connected with one another via buses  36 - 0  to  36 - 3 . 
         [0064]    As the computer for using the information processing system  10 , a storage request computer  24  and an analysis request computer  25  are provided and each include central processing devices  30 - 4 ,  30 - 5 , main storage devices  31 - 4 ,  31 - 5 , secondary storage devices  32 - 4 ,  32 - 5 , network interfaces  33 - 4 ,  33 - 5 , input devices  34 - 4 ,  34 - 5 , and output devices  35 - 4 ,  35 - 5  therein, and their elements are mutually connected with one another via buses  36 - 4 ,  36 - 5 . 
         [0065]    The central processing devices  30 - 0  to  30 - 5  include a central processing unit (CPU) and a micro processing unit (MPU). The main storage devices  31 - 0  to  31 - 5  include a random access memory (RAM) and a read only memory (ROM). The secondary storage devices  32 - 0  to  32 - 5  include a hard disk drive (HDD) and a semiconductor disk (solid state disk ((SSD)). The network interfaces  33 - 0  to  33 - 5  include an Ethernet network interface card (NIC). Further, the management computer  20 , the processing computers  21 - 1  to  21 - 3 , the storage request computer  24 , and the analysis request computer  25  are mutually, communicably connected with one another via the network interfaces  33 - 0  to  33 - 5  included in each computer by a network  37 . Furthermore, the input devices  34 - 0  to  34 - 5  for using the information processing system  10  include devices such as a keyboard and a mouse. The output devices  35 - 0  to  35 - 5  include a device such as a liquid crystal monitor. 
         [0066]    With reference to  FIG. 1 , a software configuration example of the management computer  20  will be described. The main storage device  31 - 0  of the management computer  20  stores a data placement determination unit  100 , a data redundancy determination unit  200 , a data structure conversion determination unit  300 , an analysis request reception unit  400 , an analysis execution location determination unit  500 , and a data recovery determination unit  600 . The processing units described above can be realized when the central processing device  30 - 0  executes a software program corresponding to a function of each processing unit, but also can be realized as a hardware. According to the present embodiment, each processing unit that can be realized when the central processing device  30 - 0  operates the each processing unit is described as a main subject for each processing, but, when the each processing unit is realized as the hardware, mainly the each processing unit performs each processing. Further, the main storage device  31 - 0  of the management computer  20  stores the data structure management table  70 . 
         [0067]    The each processing unit of the software of the management computer  20  will be described below. 
         [0068]    When the file is stored in the information processing system  10 , the data placement determination unit  100  determines to which processing computer  21  the storage request computer  24  should first transmit the file, and then performs processing for giving the instruction to the storage request computer  24 . Hereinafter, the file first transmitted by the storage request computer  24  to the information processing system  10  is referred to as an “original file”. 
         [0069]    The data redundancy determination unit  200  performs, on the file stored in the processing computer  21 , processing for giving an instruction of file redundancy so as to satisfy a redundancy level of the file according to (refer to  FIG. 3 ) the policy definition file  50 . 
         [0070]    The data structure conversion determination unit  300  performs, on the file made redundant in the information processing system  10  by the data redundancy determination unit  200 , the processing for giving an instruction of data structure conversion processing or data structure reverse-conversion processing on a file made redundant to satisfy a retention ratio of the data structure according to the policy definition file  50  (refer to  FIG. 3  for details). Details of the data structure conversion processing and the data structure reverse-processing will be described later. 
         [0071]    The analysis request reception unit  400  receives an analysis request transmitted from the analysis request computer  25  and performs processing for invoking the analysis execution location determination unit  500 . 
         [0072]    The analysis execution location determination unit  500  analyzes the analysis request from the analysis request computer  25  received by the analysis request reception unit  400 , determines the processing computer  21  that performs the analysis processing using setting of an analysis request setting screen  61  (refer to  FIG. 4 ), and then instructs the analysis processing in response to the analysis request. 
         [0073]    To maintain the redundancy level of the file according to the policy definition file  50  (refer to  FIG. 3 ) when the failure occurs with the computer, the data recovery determination unit  600  performs processing for giving an instruction to the each processing computer  21  to recover the file as necessary. 
         [0074]    With reference to  FIG. 1 , configuration elements of the management computer  20  and the secondary storage device  32 - 0  will be described. The secondary storage device  32 - 0  of the management computer  20  stores a computer definition file  40  (refer to  FIG. 2 ), a policy definition file  50  (refer to  FIG. 3 ), and an analysis request setting file  60 . Details of each element will be described below. 
         [0075]    With reference to  FIG. 1 , a software configuration example of the processing computers  21 - 1 ,  21 - 2 ,  21 - 3  will be described. Since the software of the processing computer  1  ( 21 - 1 ), the processing computer  2  ( 21 - 2 ), and the processing computer  3  ( 21 - 3 ) have the same configuration, the software configuration of the processing computer  1  ( 21 - 1 ) is representatively described as an example. The main storage device  31 - 1  stores a data storage unit  1000 , a data redundancy unit  1100 , a data structure conversion unit  1200 , a data structure reverse-conversion unit  1300 , and an analysis processing unit  1400 . The processing units described above can be realized when the central processing device  30 - 1  executes the software program corresponding to the function of each processing unit, but also can be realized as the hardware. According to the present embodiment, each processing unit that can be realized when being operated by the central processing device  30 - 1  is described as a main subject of each processing, but, when the each processing unit is realized by the hardware, mainly the each processing unit performs each processing. 
         [0076]    With reference to  FIG. 1 , the each processing unit of the software of the processing computer  1  ( 21 - 1 ) will be described. 
         [0077]    The data storage unit  1000  receives the file transmitted from the storage request computer  24  and performs the processing for storing the file in the secondary storage device  32 - 1  in the processing computer  1  ( 21 - 1 ). 
         [0078]    Upon reception of the instruction given by the data redundancy determination unit  200  of the management computer  20 , the data redundancy unit  1100  performs processing for transmitting the file stored in the secondary storage device  32 - 1  of the process computer  1  ( 21 - 1 ) to another computer. 
         [0079]    The data structure conversion unit  1200  and the data structure reverse-conversion unit  1300  perform processing for converting or reverse-converting the data structure of the file stored in the secondary storage device  32 - 1  in the processing computer  1  ( 21 - 1 ). The data structure conversion unit  1200  performs processing for receiving a file name as an input, and converting the data structure of the file into that of a converted file. Hereinafter, the file converted and output by the data structure conversion unit  1200  is referred to as a “converted file”. Further, the data structure reverse-conversion unit  1300  outputs an original data obtained by reverse-converting the data structure of the input converted file. Specific examples of the conversion and the reverse conversion will be described below. According to the present embodiment, as the data structure of the original file, a comma separated values (CSV) format is described as an example. However, the present invention can be adopted to the data structure such as an XML format or a ZIP compression format as long as the data can be reverse-converted according to a certain rule. The data structure conversion unit  1200  performs processing for transposing the data from row data to column data in the CSV file, and the data structure reverse-conversion unit  1300  performs processing for transposing the data from the column data to the row data therein. 
         [0080]    Upon reception of the instruction given by the analysis execution location determination unit  500  operated by the management computer  20 , the analysis processing unit  1400  performs processing for analyzing a query included in the analysis request, analyzing the data in the file stored in the secondary storage device  32 - 1  of the processing computer  1  ( 21 - 1 ), and then returning an analysis result to the analysis request computer  25 . According to the present embodiment, a language similar to the structured query language (SQL) is used as a query language, but any data analysis language can be adopted to the present invention. The analysis processing unit  1400  performs processing for analyzing the query used by the information processing system  10  on the file in the CSV format stored in the secondary storage device  32 - 1 , and returns a result. 
         [0081]    With reference to  FIG. 1 , configuration elements of the secondary storage devices  32 - 1  to  32 - 3  of the processing computers  21 - 1  to  21 - 3  respectively will be described. The secondary storage devices  32 - 1  to  32 - 3  of the processing computers  21 - 1  to  21 - 3  store files  80 - 1  to  80 - 3  respectively managed by the information processing system  10 . The files  80 - 1  to  80 - 3  managed by the information processing system  10  are stored as either of the original file and the converted file in which the data structure has been converted. The file stored in each of the computers  21 - 1  to  21 - 3  is not limited to one file but a plurality of files may be stored. 
         [0082]    The computer definition file  40  will be described. Fig. illustrates a configuration example of the computer definition file  40 . The computer definition file  40  is stored in the secondary storage device  32 - 0  of the management computer  20 . Processing computers  41  to  43  managed by the management computer  20  are specified for computer definition file  40 . According to the present embodiment, host names (processing computers  1  to  3 ) of each of the processing computers  21 - 1  to  21 - 3  are used to specify the processing computer, but, a method of using an IP address can be also specified in which each of the processing computers  21 - 1  to  21 - 3  can be uniquely specified. 
         [0083]    The policy definition file  50  will be described below.  FIG. 3  illustrates a configuration example of the policy definition file  50 . The policy definition file  50  is stored in the secondary storage device  32 - 0  of the management computer  20 . A redundancy level  51  of the file indicating in how many layers the files are retained for redundancy can be defined for the policy definition file  50 . Further, of the file retained in a plurality of layers in the system, a retention ratio  52  between the original file and the converted file that defines the retention ratio of the data structure can be defined. For example, when it is defined that the redundancy level of the file is “3” and the retention ratio between the original file and the converted file is 2:1, with reference to the policy definition file  50 , the management computer  20  stores total three files including two original files before conversion and one converted file after conversion for each file stored in the information processing system  10  distributedly into each of the processing computers  21 - 1  to  21 - 3 . 
         [0084]      FIG. 4  illustrates a screen example of the analysis request setting screen  61  for editing the analysis request setting file  60  to be stored in the secondary storage device  32 - 0  of the management computer  20 . Inputting/outputting to/from the screen are performed via the input device  34 - 0  and the processing computer  35 - 0  of the management computer  20 , but the input and output processing can be performed via the input device and the output device of another computer. As to the query specified when the analysis request is issued from the analysis request computer  25  to the information processing system  10 , user using the information processing system  10  can explicitly specify whether the converted file is used for each query. According to the example of the screen illustrated in  FIG. 4 , it is defined that, when any file is analyzed, a query  62  for calculating a total value of specific column values and a query  63  for calculating an average value thereof use the converted file. Further, it is defined that a query  64  for extracting a value of a specific column, when any file is analyzed, uses the converted file if the number of the columns is specified as “1” or more and “4” or less. For the query that has not been defined in the screen, the original file is used. Furthermore, for a list  65  in which the query is registered, the user can freely add or delete the query using an addition button  66  or a deletion button  67 . The queries  62 ,  63 ,  64  defined in the screen are an example, and the queries are not limited thereto. According to the present embodiment, the query language of the SQL base is used, but, other general query languages can be also used. 
         [0085]    The data structure management table  70  will be described.  FIG. 5  illustrates a configuration example of the data structure management table  70 . The data structure management table  70  is stored in the main storage device  31 - 0  of the management computer  20 . The columns  71 - 1  to  71 - 3  of the data structure management table  70  represent the files and their formats retained in the secondary storage devices  32 - 1  to  32 - 3  of the processing computers  21 - 1  to  21 - 3  respectively. Further, rows  72 -A to  72 -C of the data structure management table  70  indicates in which processing computers  21 - 1  to  21 - 3  and in which storage format a certain file is retained. The example illustrated in  FIG. 5  indicates a retention state of the file disposed in each processing computers  21 - 1  to  21 - 3 , with three processing computers  21 - 1  to  21 - 3  and the files of three types set. In  FIG. 5 , retaining the original file that has not yet converted is represented as “0” and retaining the converted file that has been converted is represented as “1”. When the processing computers  21 - 1  to  21 - 3  retain no files, “−1” is indicated. 
         [0086]    An example of what is meant in the data structure management table  70  will be described below. In the data structure management table  70  illustrated in  FIG. 5 , the column  71 - 1  represents that the processing computer  1  stores the original files before conversion of the files A and C and the converted file after conversion of the file B in the secondary storage device  32 - 1 . Further, the row  72 -A represents that the original file before conversion of the file A is stored in the processing computer  1  and the processing computer  2 , and the converted file after conversion of the file A is stored in the secondary storage devices  32 - 1  to  32 - 3  of the processing computer  3 . 
         [0087]    Finally, an example of an updating method of the data structure management table  70  will be described. Since the data structure management table  70  represents the file retained by each of the processing computers  21 - 1  to  21 - 3  and their structures, when it is updated, the formats of the files retained by all processing computers  21 - 1  to  21 - 3  are checked to update each of items  73 -A 1  to  73 -C 3  of the data structure management table  70 . 
         [0088]      FIG. 6  illustrates an example of a file when it is assumed that the processing is performed according to the present embodiment and its format. According to the present embodiment, the original file  81  transmitted to the information processing system  10  by the storage request computer  24  is the file in the CSV format in which one line is treated as one record and a value of each record is divided with a comma, which is a dividing character. The data structure conversion unit  1200  according to the present embodiment performs data structure conversion processing  83 , which is the conversion processing for transposing the row and the column of the CSV file with each other to store them. The converted file  82  in which the row and the column of the original file are transposed with each other by the data structure conversion unit  1200  is also the file in the CSV format. The data structure reverse-conversion unit  1300  according to the present embodiment performs the data structure reverse-conversion processing  84 , which is the conversion processing for transposing the row and the column with each other again, on the converted file  82  in which the row and the column is transposed with each other by the data structure conversion unit  1200 . In other words, if the data structure conversion unit  1200  adopts the data structure conversion processing  83  on the original file  81  and, after obtaining the converted file  82 , the data structure reverse-conversion unit  1300  further adopts the data structure reverse-conversion processing  84 , the original file  81  can be obtained. Details of the data structure conversion processing  83  and the data structure reverse-conversion processing  84  will be described below. 
         [0089]    The present embodiment will be described, using the file in the CSV format as the original file and the converted file, and based on a processing example in which the row and the column of the file in the CSV format are transposed with each other as the data structure conversion processing and the data reverse-conversion processing. However, as other examples, other conversion processing and reverse-conversion processing can be adopted that include combination of an expanded file and a compressed file as the original file and the converted file, compression processing as the data structure conversion processing, and expansion processing as the data structure reverse-conversion processing, and combination of a decoded file and an encrypted file as the original file and the converted file, the encryption processing as the data structure conversion processing, and the decoding processing as the data structure reverse-conversion processing. 
         [0090]    File copy processing by the information processing system  10  will be described.  FIG. 7  is an example of a sequence diagram illustrating processing when the file is copied to the information processing system  10  from the storage request computer  24 . 
         [0091]    When the storage request computer  24  copies the file to the information processing system  10 , the storage request computer  24  issues a file storage request (S 2001 ) to the management computer  20 . Upon reception of the file storage request (S 2001 ) from the storage request computer  24 , the data placement determination unit  100  of the management computer  20  performs data placement determination processing (S 2002 ), and notifies the storage request computer  24  of a host name of the processing computer  21  which is to be a storage destination (S 2003 ). According to the example of the sequence diagram, the data placement determination unit  100  selects the processing computer  1  ( 21 - 1 ) as the processing computer  21  of the storage destination of the file. Details of the data placement determination processing (S 2002 ) performed by the data placement determination unit  100  will be described below. The storage request computer  24  receives a content of a storage destination computer instruction (S 2003 ) from the management computer  20 , and transmits the file to the processing computer  1  ( 21 - 1 ) (S 2004 ). The processing computer  1  ( 21 - 1 ) receives the file transmitted by the storage request computer  24  and, by the data storage processing (S 2005 ) performed by the data storage unit  1000 , stores the file in the secondary storage device  32 - 1  of the processing computer  1  ( 21 - 1 ) illustrated in  FIG. 1 . The file stored at this point is specified as an “original file” hereinafter. After the original file is stored, the processing computer  1  ( 21 - 1 ) transmits storage completion notifications (S 2006 , S 2007 ) to the management computer  20  and the storage request computer  24 . 
         [0092]    After the storage completion notification (S 2007 ) from the processing computer  1  ( 21 - 1 ) is received, by the data redundancy determination processing (S 2008 ) performed by the data redundancy determination unit  200 , the management computer  20  gives data redundancy instruction (S 2009 ) of the original file. Details of the data redundancy determination processing (S 2008 ) will be described below. The data redundancy instruction (S 2009 ) including the host name of the processing computer  21 , which is a data redundancy destination, is transmitted to the processing computer  1  ( 21 - 1 ) by data redundancy determination processing (S 2008 ), and the processing computer  1  ( 21 - 1 ) performs data redundancy processing (S 2010 ). The data redundancy processing (S 2010 ) copies the specified file to another processing computer  21 . As a result of the data redundancy processing (S 2010 ), the processing computer  21  of the transmission destination of the original file can be specified. Herein, as an example, the original file stored in the secondary storage device  32 - 1  of the processing computer  1  ( 21 - 1 ) is transmitted to the processing computer  2  ( 21 - 2 ) and the processing computer  3  ( 21 - 3 ). After the original file transmitted by the processing computer  1  ( 21 - 1 ) is received, the processing computer  2  ( 21 - 2 ) and the processing computer  3  ( 21 - 3 ) store the original file into each of the secondary storage devices  32 - 2 ,  32 - 3  by the data storage processing (S 2013 , S 2014 ). Finally, the processing computer  2  ( 21 - 2 ) and the processing computer  3  ( 21 - 3 ) transmit the storage completion notifications (S 2015 , S 2016 ) respectively to the management computer  20 . 
         [0093]    After the management computer  20  receives the storage completion notifications (S 2015 , S 2016 ) from the processing computer  2  ( 21 - 2 ) and the processing computer  3  ( 21 - 3 ) respectively, an instruction for converting the data structure is given by the data structure conversion determination processing (S 2017 ). Details of the data structure conversion determination processing (S 2017 ) will be described below. By the data structure conversion determination processing (S 2017 ), the processing computer  21  for performing the data structure conversion processing is specified. Herein, as an example, the data structure conversion instruction (S 2018 ) including the file name of the file on which the data structure conversion processing is to be performed is transmitted to the processing computer  3  ( 21 - 3 ). After receiving the data structure conversion instruction (S 2018 ), the processing computer  3  ( 21 - 3 ) performs data structure conversion processing (S 2019 ). Based on the file name included in the data structure conversion instruction (S 2018 ), the data structure conversion processing (S 2019 ) performs processing for converting the data structure of the file stored in the secondary storage device  32 - 3  of the processing computer  3  ( 21 - 3 ) to transpose the original file into the converted file. Details of the data structure conversion processing (S 2019 ) will be described below. After the data structure is converted, the processing computer  3  ( 21 - 3 ) transmits conversion completion notification (S 2020 ) to the management computer  20 . As described above, the processing when the storage request computer  24  copies the file to the information processing system  10  is completed. 
         [0094]    The data placement determination processing (S 2002 ) performed by the data placement determination unit  100  will be described below.  FIG. 8  is a flowchart illustrating an example of the data placement determination processing (S 2002 ). In step S 101 , upon start of processing in step S 100 , the data placement determination unit  100  receives the file storage request from the storage request computer  24 . The file storage request corresponds to the file storage request (S 2001 ) illustrated in  FIG. 7 . In step S 102 , a list of the processing computers  21  is read from the computer definition file  40  illustrated in  FIG. 2 . In step S 103 , from among the read list of the processing computers  21 , one computer to which the file to be firstly transmitted by the storage request computer  24  is randomly selected. The computer selected herein corresponds to the processing computer  1  ( 21 - 1 ) illustrated in  FIG. 7 . Finally, in step S 104 , to give an instruction for transmitting the file to the selected processing computer  21  to the storage request computer  24 , the data placement determination unit  100  transmits the storage destination computer instruction to the storage request computer  24 . The storage destination computer instruction herein corresponds to the storage destination computer instruction (S 2003 ) illustrated in  FIG. 7 . In step S 105 , the data placement determination processing (S 2002 ) performed by the data placement determination unit  100  is ended. 
         [0095]    The data redundancy determination processing (S 2008 ) performed by the data redundancy determination unit  200  will be described below.  FIG. 9  is a flowchart illustrating an example of the data redundancy determination processing (S 2008 ). In step S 201 , upon start of the processing in step S 200 , the data redundancy determination unit  200  receives the storage completion notification that has been transmitted from the processing computer  21  and is determined by the data placement determination unit  100 . The storage completion notification corresponds to the storage completion notification (S 2007 ) illustrated in  FIG. 7 . In step S 202 , the redundancy level  51  of the file to be stored is read from the policy definition file  50  illustrated in  FIG. 3 . In step S 203 , of the processing computers  21  described in the computer definition file  40 , the list of the processing computers  21  other than the processing computer  21  selected by the data placement determination processing (S 2002 ) illustrated in  FIG. 8  is read. In step S 204 , from the list of the read processing computers  21 , the redundancy destination computers of (redundancy level of the file −1) are selected. According to the sequence diagram illustrated in  FIG. 7 , the redundancy level of the storage target file is “3”. Since the processing computer  1  ( 21 - 1 ) is selected in the data placement determination processing (S 2002 ), the processing computer  2  ( 21 - 2 ) and the processing computer  3  ( 21 - 3 ) are selected as the redundancy destination computer in step S 204 . Finally, in steps S 205  to S 207 , to give the instruction for the data redundancy to all redundancy destination computers selected in step S 204 , the data redundancy instruction is transmitted to the processing computer  21  selected in the data placement determination processing (S 2002 ) and, in step S 208 , the processing is ended. The data redundancy instruction herein corresponds to the data redundancy instruction (S 2009 ) illustrated in  FIG. 7 . 
         [0096]    The data structure conversion determination processing (S 2017 ) performed by the data structure conversion determination unit  300  will be described below.  FIG. 10  is a flowchart illustrating an example of the data structure conversion determination processing (S 2017 ). In the data structure determination processing (S 2017 ), of the redundant file on which the data redundancy determination processing (S 2008 ) and the data redundancy processing (S 2010 ) are performed, according to the definition of the policy definition file  50  illustrated in  FIG. 3 , processing for determining and instructing whether the data structure needs to be converted is performed. With reference to  FIG. 10 , the processing will be described below. 
         [0097]    In step S 301 , upon start of the processing in step S 300 , the data structure conversion determination unit  300  receives all storage completion notifications returned from the data storage processing (S 2013 , S 2014 ) performed by the each processing computer  21  by the data redundancy determination processing (S 2008 ) and the data redundancy processing (S 2010 ). The storage completion notification herein corresponds to the storage completion notifications (S 2015 , S 2016 ) illustrated in  FIG. 7 . In step S 302 , the data structure conversion determination unit  300  reads the redundancy level  51  of the file and the retention ratio  52  between the original file and the converted file from the policy definition file  50  as illustrated in  FIG. 2 . In step S 303 , the data structure conversion determination unit  300  calculates the target number of the retained, converted files based on the redundancy level  51  of the file read in step S 302  and the retention ratio  52  between the original file and the converted file. More specifically, the target number of the retained, converted files can be calculated by a×c/(b+c) (round down after the decimal point) when the redundancy level of the file is defined as “a” and the retention ratio is defined as “b:c”. 
         [0098]    With reference to the data structure management table  70  illustrated in  FIG. 5 , the data structure conversion determination unit  300  repeatedly performs steps S 304  to S 309  until the current number of the retained, converted files corresponds to the target number of the retained, converted files calculated in step S 303 . When the current number of the retained, converted files does not correspond to the target number thereof calculated in step S 303 , the both numbers described above are further compared with each other. When it is determined that the current number of the retained, converted file is smaller than the target number thereof in step S 305  (the current number is smaller), then in step S 306 , the data structure conversion determination unit  300  performs processing of step S 306  to select one processing computer  21  storing the original file and instruct conversion of the data structure. The conversion instruction of the data structure includes the name of the file to be converted. Further, when it is determined that the current number of the retained, converted file is larger than the target number thereof in step S 305  (the current number is larger), then in step S 307 , the data structure conversion determination unit  300  performs processing of step S 307  to select one processing computer storing the converted file and instruct the reverse-conversion of the data structure. The reverse-conversion instruction of the data structure includes the name of the file to be converted. Finally, in S 308 , the data structure conversion determination unit  300  updates the data structure management table  70 , and returns to step S 304  until the current number of the retained, converted files corresponds to the target number thereof. 
         [0099]    For example, when the redundancy level  51  of the storage target file recorded in the policy definition file  50  is “3”, and the retention ratio  52  between the original file and the converted file is 2:1, at the time of first step S 305 , by the data redundancy determination processing (S 2008 ) illustrated in  FIG. 7 , the number of the retained original files is “3” and the number of the retained converted file is “0”. Further, the target number of the retained, converted files is “1” based on the calculation of the target number thereof obtained in step S 303 . Therefore, step S 306  is performed and, in step S 310 , the original file is converted into the converted file and the current number of the retained, converted files becomes “1”, and the processing is ended since the current number thereof corresponds to the target number thereof. 
         [0100]    The data structure conversion processing (S 2019 ) performed by the data structure conversion unit  1200  will be described below.  FIG. 11  is a flowchart illustrating an example of the data structure conversion processing (S 2019 ). The data structure conversion processing (S 2019 ) performs processing for creating and storing the converted file, in which the row and the column are transposed with each other, on the original file in the CSV format illustrated in  FIG. 6 . With reference to  FIG. 11 , the processing will be described below. 
         [0101]    In step S 1201 , upon start of the processing in step S 1200 , the data structure conversion unit  1200  receives a data structure conversion instruction from the management computer  20 . The data structure conversion instruction corresponds to the data structure conversion instruction (S 2018 ) illustrated in  FIG. 7 . The data structure conversion instruction includes the file name of the file to be converted, and the file is referred to as an original file. The file created by the data structure conversion processing is referred to as a converted file. 
         [0102]    In step S 1202 , the data structure conversion unit  1200  opens the original file and creates an empty converted file. The data structure conversion unit  1200  repeatedly performs steps S 1203  to S 1205  for performing transposition processing for each row on values of each column of the original file. In step S 1204 , in the processing, the value of each column is sequentially read, converted into the file in the CSV format in one line divided with a comma in an order of being read, and then added to the converted file. After the processing of steps S 1203  to S 1205  is performed, in step S 1206 , the original file and the converted file are closed, in step S 1207 , the original file is replaced with the converted file, and then in step S 1208 , the processing is ended. As described with reference to  FIG. 6 , the processing for transposing the row and the column in the CSV format as the data structure conversion processing is an example according to the present embodiment, and the processing is not limited thereto. 
         [0103]    The data structure reverse-conversion processing performed by the data structure reverse-conversion unit  1300  will be described below.  FIG. 12  is a flowchart illustrating an example of the data structure reverse-conversion processing. The data structure reverse-conversion processing performs processing for creating and storing the converted file, in which the row and the column are transposed with each other, on the converted file in the CSV format illustrated in  FIG. 6 . With reference to  FIG. 12 , the processing will be described below. 
         [0104]    In step S 1301 , upon start of the processing in step S 1300 , the data structure reverse-conversion unit  1300  receives the data structure reverse-conversion instruction from the management computer  20 . The data structure reverse-conversion instruction includes the file name of the file to be reverse-converted. The file is referred to as the converted file, and the file created by the data structure reverse-conversion processing is referred to as the original file. 
         [0105]    In step S 1302 , the data structure reverse-conversion unit  1300  opens the converted file, and creates an empty original file. 
         [0106]    The data structure reverse-conversion unit  1300  repeatedly performs steps S 1303  to S 1305  for performing the transposition processing for each column on the value of each column of the converted file. In step S 1304 , in the transposition processing, the values of each column are sequentially read, converted into those in the CSV format in one line divided with a comma in an order of being read, and then added to the original file. In step S 1306 , after performing the processing of steps S 1303 , S 1304 , and S 1305 , the data structure reverse-conversion unit  1300  closes the converted file and the original file. Instep S 1307 , the data structure reverse-conversion unit  1300  replaces the converted file with the original file and then, in step S 1308 , the data structure reverse-conversion unit  1300  ends the processing. As described with reference to  FIG. 6 , the processing for transposing the row and the column in the CSV format with each other as the data structure reverse conversion processing is an example according to the present embodiment, and the processing is not limited thereto. 
         [0107]    The analysis request processing by the information processing system  10  according to the present embodiment will be described below.  FIG. 13  is an example of a sequence diagram when the information processing system  10  receives the analysis request from the analysis request computer  25 . The analysis request computer  25  transmits the analysis request including the query to the management computer  20 . The management computer  20  receives the analysis request from the analysis request computer  25  by analysis request reception processing (S 2102 ), and determines the computer for performing the analysis by analysis execution location determination processing (S 2103 ). Details of the analysis execution location determination processing (S 2103 ) will be described below. 
         [0108]    The management computer  20  transmits an analysis instruction (S 2104 ) to the processing computer  21  determined by the analysis execution location determination processing (S 2103 ). According to the example of the sequence diagram, the analysis execution location determination processing (S 2103 ) selects the processing computer  3  ( 21 - 3 ), which is not limited. The processing computer  3  ( 21 - 3 ) that has received the analysis instruction (S 2104 ) performs the analysis by the analysis processing (S 2105 ), and transmits the analysis result (S 2106 ) to the analysis request computer  25 . With the processing described above, the analysis request computer  25  can obtain the analysis result (S 2106 ) for the analysis request (S 2101 ). 
         [0109]    The analysis execution location determination processing (S 2103 ) performed by the analysis execution location determination unit  500  will be described below.  FIG. 14  is a flowchart illustrating an example of the analysis execution location determination processing (S 2103 ). Upon start of the processing in step S 500 , in step S 501 , the analysis execution location determination unit  500  reads the list of the queries using the converted file from the analysis request setting file  60  that can be edited via the analysis request setting screen  61  illustrated in  FIG. 4 . In step S 502 , it is checked whether the query received by the analysis request reception processing (S 2102 ) is included in the list of the queries using the converted file read in step S 501 . When it is determined that the query is included in the list of the queries using the converted file (“included” in step S 502 ), the analysis execution location determination unit  500  proceeds to the processing in step S 503 . When it is determined that the query is not included in the list (“not included” in step S 502 ), the processing proceeds to step S 504 . 
         [0110]    When the processing proceeds to step S 503 , in step S 503 , the analysis execution location determination unit  500  selects one processing computer  21  storing the converted file from the data structure management table  70  illustrated in  FIG. 5 . On the other hand, when the processing proceeds to step S 504 , in step S 504 , the analysis execution location determination unit  500  selects one processing computer storing the original file from the data structure management table  70  illustrated in  FIG. 5 . In either of steps S 503  and S 504 , when a plurality of computers to become a candidate are included, one computer is randomly selected from the plurality of computers. Finally, in step S 505 , the analysis execution location determination unit  500  instructs the analysis processing to the computer selected in either step of steps S 503  and S 504  and, in step S 506 , the processing is ended. The analysis instruction herein corresponds to that of S 2104  illustrated in  FIG. 13 . 
         [0111]    Recovery processing of the file when the failure occurs with the processing computer  21  in the information processing system  10  will be described below.  FIG. 15  is an example of a sequence diagram illustrating recovery processing of the file when the failure occurs with the processing computer  21  in the information processing system  10 . This sequence diagram illustrates an example of a case where, when the failure occurs with the processing computer  2  ( 21 - 2 ), the file is recovered by the processing computer  2 ′ ( 21 - 2 ′) to guarantee the redundancy level of file. With reference to  FIG. 15 , the processing will be described below. 
         [0112]    The management computer  20  periodically performs failure detection processing (S 2201 ) and checks whether no failure has occurred with each processing computer  21  described in the computer definition file  40  illustrated in  FIG. 2 . According to the example of the sequence diagram, it is checked whether no failure has occurred with the processing computer  1  ( 21 - 1 ), the processing computer  2  ( 21 - 2 ), the processing computer  3  ( 21 - 3 ), and the processing computer  2 ° ( 21 - 2 ′). Since the failure detection processing (S 2201 ) can be realized by an existing method described below, it is not described herein. An example of the method of the failure detection processing includes a method for performing a life-or-death monitor of the computer by availability of network communication to each computer, and a method for performing the life-or-death monitor thereof when the management computer  20  refers to management information collected and notified by each processing computer. 
         [0113]    When the management computer  20  detects the failure of the processing computer  21  by the failure detection processing (S 2201 ) of the management computer  20 , since the redundancy of the file stored in the information processing system  10  is highly possibly lost, the recovery processing of the data needs to be performed. To determine whether the recovery processing is necessary, the management computer  20  performs the data recovery determination processing (S 2202 ). 
         [0114]    In the data recovery determination processing (S 2202 ) performed by the data recovery determination unit  600 , it is checked whether the redundancy of each file stored in the processing computer  21  with which the failure has occurred, which is detected by failure detection processing, is not lost (S 2201 ). When the redundancy is lost, the file whose redundancy is lost is recovered by another processing computer  21 . According to the example of the sequence diagram, when the failure has occurred with the processing computer  2  ( 21 - 2 ), the data recovery determination unit  600  specifies that the processing computer  3  ( 21 - 3 ) retains the file lost due to the failure, and the file is transmitted from the processing computer  3  ( 21 - 3 ) to the processing computer  2 ′ ( 21 - 2 ′). A specific procedure for recovering the file is included in an instruction of the data redundancy processing, an instruction of the data structure conversion, or an instruction of the data structure reverse-conversion. Details will be described below. 
         [0115]    Data recovery determination processing (S 2202 ) performed by the data recovery determination unit  600  will be described below.  FIG. 16  is a flowchart illustrating an example of the data recovery determination processing (S 2202 ). In the data recovery determination processing (S 2202 ), of all files stored in the processing computer  21  with which the failure has occurred, processing is performed for giving an instruction for recovering with another processing computer  21  on the file that does not satisfy the redundancy level  51  of the file in the policy definition file  50  illustrated in  FIG. 3 . Further, after the file is recovered, to adjust the retention ratio  52  of the data structure, processing is also performed for giving an instruction for performing the conversion or the reverse-conversion of the data structure. With reference to  FIG. 16 , the processing will be described below. 
         [0116]    Upon start of the processing in step S 600 , in step S 601 , the data recovery determination unit  600  obtains all information about the file stored in the processing computer  21  with which the failure has occurred, with reference to the data structure management table  70  illustrated in  FIG. 5 . Processing of steps S 602  to S 611  is repeatedly performed on the all files whose information is obtained. In step S 603 , in a loop from step S 602  to step S 611 , it is determined whether each file satisfies the redundancy level  51  of the file defined in  FIG. 3 . When it is determined that the redundancy level  51  is satisfied (“satisfying” in step S 603 ), the data recovery determination unit  600  does not perform subsequent processing of the step S 603 , and returns to the processing in step S 602 . On the other hand, when it is determined that the redundancy level  51  is not satisfied (“not satisfying” in step S 603 ), the data recovery determination unit  600  proceeds to the processing in step S 604 . 
         [0117]    In step S 604 , for the file to be recovered, the data recovery determination unit  600  selects one computer as a computer of a recovery source from among the computers retaining both the original file and the converted file. When there is a plurality of computers to become a candidate, the computer is randomly selected. Further, in step S 605 , for the file to be recovered, from among the computers retaining none of the original file nor the converted file, one computer is selected as a computer of a recovery destination. In this case also, when there is a plurality of computers to become a candidate, the computer is randomly selected. In step S 606 , the data recovery determination unit  600  gives an instruction of the data redundancy processing of the file to be recovered to the recovery destination computer selected in step S 605  to the recovery source computer selected in step S 604 . The data redundancy instruction corresponds to the data redundancy instruction illustrated in  FIG. 15  (S 2203 ). With the processing described above, the redundancy level  51  of the file to be recovered can be recovered to a state before the failure has occurred. 
         [0118]    Further, in step S 607 , the data structure of the file stored in the computer with which the failure has occurred is compared with the data structure of the file copied in steps S 604  to S 606 . As a result of the comparison, when it is determined that the data structure is the same (“same” in step S 607 ), the data recovery determination unit  600  proceeds to processing in step S 611 . On the other hand, when it is determined that the data structure is different (“different in step S 607 ), then in step S 608 , the data recovery determination unit  600  proceeds to processing of step S 608  and checks the data structure of the file of the recovery source selected in step S 604 . When it is determined that the data structure of the file of the recovery source is the original file (“original file” in step S 608 ), the data recovery determination unit  600  proceeds to processing step S 609  and, in step S 609 , performs an instruction of the data structure conversion processing on the computer of the recovery destination selected in step S 605 . On the other hand, when it is determined that the data structure of the recovery source is the converted file (“converted file” in step S 608 ), then in step S 610 , the data recovery determination unit  600  gives an instruction of the data structure reverse-conversion processing on the computer of the recovery destination selected in step  9605 . With the processing described above, the retention ratio  52  of the data structure of the file to be recovered can be recovered to the state before the failure has occurred. When the processing computer  21  storing the data to be recovered in the same data structure as that retained in the processing computer  21  with which the failure has occurred, is selected as the recovery source computer, the data conversion processing at the recovery destination may not be performed. In this case, with reference to the data structure management table  70 , the management computer  20  may select the processing computer  21  storing the data to be recovered in the same data structure as that of the data stored in the processing computer  21  with which the failure has occurred, as the recovery source computer. 
         [0119]    After repeatedly performing from step S 602  to step S 611  on all files stored in the computer with which the failure has occurred, in step S 612 , the data recovery determination unit  600  updates information in the data structure management table  70  and, in step S 613 , ends the processing. 
       Second Embodiment 
       [0120]    Next, a description will be given of the present invention according to a second embodiment thereof. In the present embodiment, there is shown an example of a system which can perform dynamic change of a retention ratio in an original file and a converted file by using statistics information of an analysis request. 
         [0121]    In the first embodiment, a retention ratio  52  of the original file and the converted file is statically defined in the policy definition file  50  shown in  FIG. 3 , and the retention ratio  52  cannot be dynamically changed during the operation of the system. In the configuration described above, when a plurality of analysis requests is concentrated on any one of the original file and the converted file, the load of the processing computer  21  processing the analysis request is biased to the specific processing computer  21  depending on an initial definition of the retention ratio  52  of the original file and the converted file, and there is a problem that it is difficult to achieve improvement of an entire performance of the system  10 . Consequently, the present embodiment records the statistics information about the analysis request, and realizes the dynamic retention ratio change of the data structure based on the recorded statistics information. 
         [0122]      FIG. 17  shows a configuration example of the system  10  according to the second embodiment. In addition to the configuration of the information processing system  10  according to the first embodiment illustrated in  FIG. 1 , a statistics information recording unit  700  and a retention ratio change determination unit  800  are added to the management computer  20 . Further, a data structure/statistics information management table  70 A is added as a table which expands the data structure management table  70 . 
         [0123]      FIG. 18  shows a configuration example of the data structure/statistics information management table  70 A. This is different from the data structure management table  70  shown in  FIG. 5  in which fields ( 74 -A to  74 -C) recording a retention ratio of the current original file, converted file, and fields ( 75 -A to  75 -C) recording the number of references for each data structure in the analysis processing are added for each file. 
         [0124]    Next, an example of what is meant in the data structure/statistics information management table  70 A will be shown. A column  71 - 1  shows that the processing computer  1  retains the original file before conversion for the files A and C and the converted file after conversion for the file B. Further, a row  72 -A shows that the processing computers  1  and  2  retain the file A as the original file before conversion, and shows that the processing computer  3  retains the file A as the converted file after conversion. 
         [0125]    A column  74  of the fields  74 -A to  74 -C recording the retention ratio indicates retention ratios of the original file and the converted file for each file. For example, in the case of the row  72 -A, since the file A is stored in the system in a state of two original files and one converted file, 2:1 is recorded in the cell  74 -A. A column  75  of the fields  75 -A to  75 -C recording the number of references indicates the number of references to the original file and the number of references to the converted file for each file. For example, in the case of the row  72 -A, 2:6 is recorded in the cell  75 -A so as to show that for the file A, the original file is referred two times in total and the converted file is referred six times in total. In the number of references  75 , the number of references during an operation period of the information processing system  10  is accumulated for each data structure so as to be recorded, but, the other recording mode may be employed, such as recording the number of references per a most recent unit time. 
         [0126]    Next, an example of an updating method of the data structure/statistics information management table  70 A is shown. First, the updating method of each of the items shown in the cells  73 -A 1  to  73 -C 3  is the same as the method shown in  FIG. 5 . Next, an updating method of the fields  74 -A to  74 -C recording the retention ratio counts up each of the number of original files and the number of converted files, in each of the corresponding rows, and records with a form (number of original files): (number of converted files) in the corresponding fields of  74 -A to  74 -C. An updating method of the fields  75 -A to  75 -C recording the number of references will be described later with reference to  FIG. 20 . 
         [0127]      FIG. 19  shows an example of a sequence diagram of the case that the analysis request computer  25  transmits the analysis request to the system  10  in the present embodiment. It is different from  FIG. 13  shown in the first embodiment in which a statistics information recording processing S 2307  is added as the processing of the management computer  20  after the analysis execution location determination processing S 2303 . 
         [0128]    A description will be given of the sequence diagram on the basis of a specific example. Three processing computers are registered in the system  10 , and files A, B and C are stored in a secondary storage device  32  of each of the processing computers  21  as shown in the data structure/statistics information management table  70 A shown in  FIG. 18 . At this time, an analysis request S 2301  is transmitted to the management computer  20  from the analysis request computer  25 . Then, the management computer  20  performs an analysis request reception processing S 2302  and the analysis execution location determination processing S 2303 , and determines to perform an analysis request S 2304  by the processing computer  3  ( 21 - 3 ). Since the analysis request reception processing S 2302  and the analysis execution location determination processing S 2303  are the same as  FIGS. 13 and 14  of the first embodiment, a description thereof will be omitted. Since the performing of the analysis processing by the processing computer  3  ( 21 - 3 ) is determined as a result of the analysis execution location determination processing S 2303 , the processing computer  3  ( 21 - 3 ) performs the analysis processing S 2305 . At this time, the management computer  20  performs a statistics information recording processing S 2307 , and performs processing for recording the performing of the analysis request transmitted from the analysis request computer  25  by the processing computer  3  ( 21 - 3 ) in the data structure/statistics information management table  70 A shown in  FIG. 18 . Details of the statistics information recording processing S 2307  will be described later. 
         [0129]    Here, a description will be given of the statistics information recording processing S 2307  which the statistics information recording unit  700  performs.  FIG. 20  is a flow chart showing an example of the statistics information recording processing S 2307 . The statistics information recording unit  700  performs processing for updating the number of references field of the data structure/statistics information management table  70 A on the basis of the processing computer  21  which is determined by the analysis execution location determination processing S 2303  performed just before, and the file which is used in the analysis processing S 2305 . When the statistics information recording unit  700  starts the processing in S 700 , in S 701 , it first selects a column of the processing computer  21  which is selected by the analysis execution location determination processing S 2303 , on the basis of the data structure/statistics information management table  70 A shown in  FIG. 18 . Next, in S 702 , it selects a row of the file which is used in the analysis request, from the selected column. Next, in S 703 , it confirms a value of a cell where the selected column and row intersect. When it is determined that the value of the cell is zero indicating the original file, the statistics information recording unit  700  proceeds to processing in S 704  (S 704 , 0). On the other hand, when it is determined that the value of the cell is one indicating the converted file, the statistics information recording unit  700  proceeds to processing in S 705  (S 705 , 1). When it proceeds to the processing in S 704 , the statistics information recording unit  700  increases a value on a left side of the number of references field of the selected row by one (S 704 ). On the other hand, when it proceeds to the processing in S 705 , the statistics information recording unit  700  increases a value on a right side of the number of references field of the selected row by one (S 705 ). The statistics information recording unit  700  finishes the processing in S 706 . 
         [0130]    Next, a description will be given of retention ratio change determination processing S 2401  which a retention ratio change determination unit  800  performs.  FIG. 21  shows an example of a sequence diagram in the case that the retention ratio of the data structure is changed for the file selected by the retention ratio change determination processing S 2401 . A timing at which the retention ratio change determination processing S 2401  is performed can be optionally set. For example, a user can manually make the retention ratio change determination unit  800  perform, and a configuration that the management computer  20  makes the retention ratio change determination unit  800  periodically perform can be applied to the present invention. Details of the retention ratio change determination processing S 2401  will be described later. Further, data structure conversion instruction S 2402  and data structure conversion processing S 2403  in the sequence diagram are only examples, and depending on determination of the retention ratio change determination processing S 2401 , there exist a case of data structure reverse-conversion instruction and data structure reverse-conversion processing. 
         [0131]    A description will be given of the sequence diagram on the basis of a specific example. A case is considered where three processing computers  21  are registered in the system  10 , and the retention ratio change determination processing S 2401  determines to change the retention ratio for a certain file A. At this time, the file A is stored in each of the processing computers  1 ,  2  and  3  as shown in the  72 -A row of the data structure/statistics information management table  70 A shown in  FIG. 18 . Further, for the file A, it is assumed that the retention ratio between the original file and the converted file is 2:1 as described in  74 -A, and the number of references of the original file and the converted file is 2:6 as described in  75 -A. 
         [0132]    As shown in  FIG. 21 , the management computer  20  first performs the retention ratio change determination processing S 2401 . Details of the retention ratio change determination processing S 2401  will be described later, but, it is determined to change the current retention ratio of 2:1 to the new retention ratio of 1:2 which is the closest to the number of references of 2:6 as a result of the performing of the retention ratio change determination processing S 2401 , in the example of the sequence diagram. Further, in order to change the current retention ratio of 2:1 to the new retention ratio of 1:2, it is determined to instruct the original file of the file A stored in the processing computer  2  ( 21 - 2 ) to convert the data structure, and the data structure conversion instruction S 2402  is transmitted to the processing computer  2  ( 21 - 2 ). In the processing computer  2  ( 21 - 2 ) having received the data structure conversion instruction S 2402 , the data structure conversion processing S 2403  is performed on the original file of the file A specified by the data structure conversion instruction, and the converted file of the file A is obtained. The data structure conversion processing S 2403  is the same as the processing shown in  FIG. 11 . The processing computer  2  ( 21 - 2 ) ends the processing by transmitting the conversion completion notification S 2404  to the management computer  20  after completion of the data structure conversion processing S 2403  for the original file of the file A. According to the above processing, the file A is changed from the state in which the retention ratio between the original file and the converted file is 2:1 to the state of the new retention ratio of 1:2 which is closer to the number of references of 2:6. 
         [0133]    Here, a description will be given of the retention ratio change determination processing S 2401  which the retention ratio change determination unit  800  performs.  FIG. 22  is a flow chart showing an example of the retention ratio change determination processing S 2401 . The retention ratio change determination unit  800  confirms whether or not the change of the ratio between the original file and the converted file is necessary for all the files stored in the system  10 , and if it is necessary, the retention ratio change determination unit  800  performs the processing of changing the retention ratio between the original file and the converted file, by determining the new retention ratio and instructing the processing computer  21  to convert or reverse-convert the data structure. A description will be given below of the processing with reference to  FIG. 22 . 
         [0134]    First, the retention ratio change determination unit  800  starts processing in S 800 , and reads a redundancy  51  of the file from the policy definition file  50  shown in  FIG. 3  (S 801 ). Hereinafter, the redundancy of the file is set to e. Next, it repeats S 802  to S 815  for all the files registered in the data structure/statistics information management table  70 A shown in  FIG. 18 . Next, it reads the retention ratios ( 74 -A to  74 -C) and the number of references ( 75 -A to  75 -C) of each of the files from the data structure/statistics information management table  70 A (S 803 ). Hereinafter, it is assumed that the read retention ratio is a:b, and the read number of references is c:d. 
         [0135]    In S 804 , the retention ratio change determination unit  800  determines whether or not the read retention ratio and the read number of references have the same tendency. An example of a specific determination method is as follows. In other words, if the difference between a value a/(a+b) and a value c/(c+d) is equal to or more than 1/(a+b), it determines that the retention ratio and the number of references have different tendencies. On the other hand, if the difference is less than 1/(a+b), it determines that the retention ratio and the number of references have the same tendency. The method of determining the tendency of the retention ratio and the number of references shown in the above description is only an example, and is not limited to this. 
         [0136]    In S 804 , if it is determined that the retention ratio and the number of references have the same tendency (same in S 804 ), the retention ratio change determination unit  800  skips the processing to a loop termination (S 815 ). On the other hand, if it is determined that the retention ratio and the number of references have the different tendencies (different in S 804 ), the retention ratio change determination unit  800  proceeds to processing in S 805 . 
         [0137]    The retention ratio change determination unit  800  determines the new retention ratio which is close to the number of references of c:d (S 805 , S 806 ). Here, an example of a method of determining the new retention ratio is listed up. In other words, the new retention ratio to be determined in the future is set to a′:b′ (a′ and b° are integral numbers which are not negative). At this time, the non-negative integer a′ in which an absolute value of a difference between a′/e and c/(c+d) is minimum is calculated. Next, b′=e−a′ is calculated. The new retention ratio of a′:b′ can be determined by the above. The determining method listed above is only an example, and the determining method is not limited to this. 
         [0138]    According to the example of the determining method described above, for example, if the redundancy (e) of the file is 3, the retention ratio of (a:b) of the original file and the converted file is 2:1, and the number of references of (c:d) is 1:2, the new retention ratio of a′:b′ is 1:2. 
         [0139]    Next, in S 807 , the retention ratio change determination unit  800  calculates a target retention number of the converted file. The target retention number here is the same as b′ which is calculated in S 806 . Next, the retention ratio change determination unit  800  repeats the processing from S 808  to S 814  until the retention number of the current converted file corresponds to the target retention number calculated in S 807 , with reference to the data structure/statistics information management table  70 A shown in  FIG. 18 . In S 809 , if the retention ratio change determination unit  800  determines that the retention number of the current converted file does not corresponds to the target retention number calculated in S 807 , it continuously compares the retention number of the current converted file with the target retention number. If it determines that the retention number of the current converted file is smaller (current is smaller in S 809 ), as a result of the comparison in S 809 , the retention ratio change determination unit  800  performs the data structure conversion processing from the original file to the converted file (S 810 ). Specifically, it selects in a random order the target computer among the processing computers  21  storing the original file so as to obtain the newly determined retention ratio, and transmits the data structure conversion instruction. It thereafter updates the data structure/statistics information management table  70 A to the most recent information in S 811 , and returns to the processing in S 808  until the retention number of the current converted file corresponds to the target retention number. 
         [0140]    On the other hand, when the retention ratio change determination unit  800  determines that the retention number of the current converted file is larger (current is larger in S 809 ), as a result of the comparison in S 809 , in S 812 , it performs the data structure reverse-conversion processing from the converted file to the original file. Specifically, it selects in a random order the target computer among the processing computers  21  storing the converted file so as to obtain the newly determined retention ratio, and transmits the reverse-conversion instruction of the data structure. In S 813 , it thereafter updates the data structure/statistics information management table  70 A to the most recent information, and returns to the processing in S 808  until the retention number of the current converted file corresponds to the target retention number. When the retention number of the current converted file corresponds to the target retention number, it finishes the processing (S 816 ). 
       Third Embodiment 
       [0141]    Next, a description will be given of a third embodiment according to the present invention. The present embodiment shows an example of a system which can perform efficient dynamic retention ratio changes of the original file and the converted file, by using statistics information of an analysis request and load information of each of the processing computers. 
         [0142]    The second embodiment proposes a configuration which realizes the dynamic retention ratio changes of the original file and the converted file on the basis of the statistics information, by the statistics information recording unit  700 , the retention ratio change determination unit  800 , and the data structure/statistics information management table  70 A. The present embodiment realizes the more efficient retention ratio change by dynamic retention ratio change while using the load information of each of the computers, at the time of dynamic retention ratio change in the second embodiment. Further, the present embodiment employs a method of copying from the processing computer  21  which already retains the file of the converted form, as a new method of the conversion processing and the reverse-conversion processing of the data structure. 
         [0143]      FIG. 23  is a view showing a configuration example of the system  10  according to the third embodiment. In comparison with the configuration according to the second embodiment illustrated in  FIG. 17 , the present embodiment is different in which a retention ratio change determination unit  800 A and a data structure conversion method determination unit  900  according to the third embodiment are added to the main storage device  31 - 0  of the management computer  20 . Further, a conversion rule definition file  90  is added to the secondary storage device  32 - 0  of the management computer  20 . In addition, a load information notification unit  1500  and a data replacement unit  1600  are added to each of the processing computers ( 21 - 1  to  21 - 3 ). 
         [0144]      FIG. 24  is an example of the conversion definition file  90  shown in  FIG. 23 . The conversion rule definition file  90  is a file which defines a condition of a threshold value of the load information such as a CPU usage rate of the processing computer  21  and a network usage rate, and processing in the case of satisfying all the conditions. In the definition example in the present embodiment, the condition of the threshold value is defined about the CPU usage rate and the network usage rate, and the processing ( 91  to  94 ) to be performed in the case of satisfying both is described. In the example in  FIG. 24 , in the case that the CPU usage rate of the processing computer  21  is as high as equal to or more than 50%, it is set so as to perform a copy processing from the processing computer  21  which has already retained the corresponding file in place of the data conversion processing in each of the processing computers  21  for reducing the load of each of the processing computers  21 . The value shown as the definition example is only an example, and can be more finely defined. Further, the CPU usage rate and the network usage rate are defined as the condition, but, the condition is not limited to them, but can be defined by the other load information of the processing computer  21  than them. 
         [0145]      FIG. 25  is an example of a sequence diagram of the case (S 2510 ) that the retention ratio change determination unit  800 A and the data structure conversion method determination unit  900  according to the present embodiment respectively perform retention ratio change determination processing S 2501  and data structure conversion method determination processing S 2508 , and instruct to perform data structure conversion processing S 2512 , and the case (S 2520 ) of instructing to perform data replacement processing S 2527 . Which of the data structure conversion processing S 2512  and the data replacement processing S 2527  is instructed to be performed is determined by the data structure conversion method determination processing S 2508 , but, details thereof will be described later. The data structure conversion instruction S 2511  and the data structure conversion processing S 2512  in the sequence diagram are only examples, and there exists the case of data structure reverse-conversion instruction and data structure reverse-conversion processing depending on the determination of the retention ratio change determination processing S 2501  and the data structure conversion method determination processing S 2508 . Details of the retention ratio change determination processing S 2501 , the data structure conversion method determination processing S 2508  and the load information notification processing S 2504  to S 2505  will be described later. Further, since the data structure conversion processing S 2512  is the same processing as  FIG. 11 , a description thereof will be omitted. 
         [0146]    A description will be given of the processing illustrated in the sequence diagram in  FIG. 25  on the basis of a specific example. The specific example assumes the case that three processing computers  21  are registered in the system  10 , and the retention ratio change determination processing S 2501  determines the retention ratio change for a certain file A. At this time, as shown in the  72 -A row of the data structure/statistics information management table  70 A shown in  FIG. 18 , the original file of the file A is stored in the processing computers  1  and  2 , and the converted file is stored in the processing computer  3 , respectively. Further, in the file A, it is assumed that the retention ratio between the original file and the converted file is 2:1 described in the cell  74 -A in  FIG. 18 , and the number of references between the original file and the converted file is 2:6 described in the cell  75 -A in  FIG. 18 . 
         [0147]    First, the management computer  20  performs the retention ratio change determination processing S 2501 . Details of the retention ratio change determination processing S 2501  according to the present embodiment will be described later, but, in the example of the sequence diagram in  FIG. 23 , it is determined to change the current retention ratio 2:1 to the new retention ratio 1:2 which is the closest to the number of references 2:6, as a result of the performing of the retention ratio change determination processing S 2501 . Further, in order to change the current retention ratio 2:1 to the new retention ratio 1:2, the management computer  20  transmits the load information notification instructions S 2502  to S 2503  to the processing computer  1  ( 2101 ) and the processing computer  2  ( 21 - 2 ). At this time, a file to be processed by the retention ratio change determination processing S 2501  is hereinafter called as a target file. The processing computer  1  ( 21 - 1 ) and the processing computer  2  ( 21 - 2 ) receiving the load information notification instructions S 2502  to S 2503  perform the load information notification processing S 2504  to S 2505 , and transmit the load information S 2506  to S 2507  to the management computer  20 . For example, the information of the CPU usage rate and the network usage rate which are described above can be included as the load information. 
         [0148]    The management computer  20  performs the data structure conversion method determination processing S 2508  after receiving the load information S 2506  to S 2507  of the processing computer  1  ( 21 - 1 ) and the processing computer  2  ( 21 - 2 ). Details of the data structure conversion method determination processing S 2508  will be described later, but, the data structure conversion method determination processing S 2508  can be separated into two patterns including a case (S 2510 ) that it selects the data structure conversion processing and a case (S 2520 ) that it selects the data replacement processing. A description will be given later of each of the patterns while separating the cases. 
         [0149]    First, a description will be given of the case that the data structure conversion processing is selected in the data structure conversion method determination processing S 2508 . As a result of the data structure conversion method determination processing S 2508 , the processing computer  2  ( 21 - 2 ) determines to perform the data structure conversion processing, and the retention ratio change determination unit  800  transmits the data structure conversion instruction S 2511  for the original file of the target file, to the processing computer  2  ( 21 - 2 ). The processing computer  2  ( 21 - 2 ) performs the data structure conversion processing S 2512  for the original file of the target file after receiving the data structure conversion instruction S 2511 , and converts the original file of the target file into the converted file. After the conversion, the processing computer  2  ( 21 - 2 ) transmits the conversion completion notification S 2513  to the management computer  20  and finishes the processing. According to the processing described above, the retention ratio between the original file A and the converted file a is changed from the state of 2:1 to the state of the new retention ratio 1:2 which is closer to the number of references 2:6. 
         [0150]    Next, a description will be given of a case that the data replacement processing is selected in the data structure conversion method determination processing (S 2508 ). As a result of the data structure conversion method determination processing S 2508 , it is determined to perform the data replacement processing between the processing computer  3  ( 21 - 3 ) and the processing computer  2  ( 21 - 2 ), and the management computer  20  transmits the data redundancy instruction S 2521  to the processing computer  3  ( 21 - 3 ) so as to make the target file redundant in relation to the processing computer  2  ( 21 - 2 ). The processing computer  3  ( 21 - 3 ) performs the data redundancy processing S 2522  in relation to the stored target file after receiving the data redundancy instruction S 2521  of the target file, and transmits the converted file of the target file to the processing computer  2  ( 21 - 2 ) (S 2523 ). The processing computer  2  ( 21 - 2 ) receiving the converted file from the processing computer  3  ( 21 - 3 ) performs the data storage processing S 2524 , stores the received converted file in the secondary storage device ( 32 - 2 ), and transmits a storage finish notification S 2525  to the management computer  20 . 
         [0151]    The management computer  20  transmits a data replacement instruction S 2526  about the converted file received from the processing computer  3  ( 21 - 3 ) and the original file which the processing computer  2  ( 21 - 2 ) originally retains, to the processing computer  2  ( 21 - 2 ) after receiving the storage finish notification S 2525 . The processing computer  2  ( 21 - 2 ) having received the data replacement instruction S 2526  performs data replacement processing S 2527  for the converted file and the original file, overwrites the original file which is originally retained in the secondary storage device ( 32 - 2 ) of the processing computer  2  ( 21 - 2 ) and is a subject to be replaced, by the converted file received from the processing computer  3  ( 22 - 3 ), and transmits a replacement finish notification S 2528  to the management computer  20 . According to the above processing, the retention ratio between the original file and the converted file is changed from the state 2:1 to the new retention ratio state 1:2 which is closer to the number of references 2:6. 
         [0152]    Next, a description will be given of a load information notification processing which the load information notification unit  1500  performs.  FIG. 26  is a flow chart showing an example of the load information notification processing. In the load information notification processing, the processing computer  21  notifies the management computer  20  of the load information of the processing computer  21  in which the load information notification unit  1500  is performed, in response to a request from the management computer  20 . 
         [0153]    When starting the processing in S 1500 , the load information notification unit  1500  receives the load information notification instruction from the management computer  20  (S 1501 ), and acquires the load information of the processing computer  21  (S 1502 ). In the load information of the processing computer  21 , for example, a disc usage rate can be included, in addition to the CPU usage rate and the network usage rate, but, load information is not limited to them. The load information notification unit  1500  notifies the management computer of the acquired load information (S 1503 ) after acquiring the load information of the processing computer  21 , and finishes the processing (S 1504 ) 
         [0154]    Next, a description will be given of the retention ratio change determination processing S 2504  to S 2505  which the retention ratio change determination unit  800 A performs.  FIG. 27  is a flow chart showing an example of the retention ratio change determination processing S 2504  to S 2505 . In comparison with the retention ratio change determining unit  800  according to the second embodiment, the retention ratio change determination unit  800 A according to the present embodiment is different in which it transmits the load information notification instruction to the processing computer  21 . In comparison with the flow chart of the retention ratio change determination processing S 2401  in the second embodiment shown in  FIG. 22 , it is different in the processing of S 850  to S 853  transmitting the load information notification instruction to the processing computer  21  which stores the original file to be applied the data structure conversion processing, or the processing computer  21  which stores the converted file to be applied the data structure reverse-conversion processing, after S 807  calculating the target retention number of the converted file. Hereinafter, a description will be given only of the different portion from  FIG. 22 . 
         [0155]    The retention ratio change determination unit  800 A calculates the target retention number of the converted file (S 807 ), and thereafter calculates an absolute value f of a difference between the retention number of the current converted file and the target retention number (S 850 ). Taking the file A in the  72 -A row of the data structure/statistics information management table  70 A shown in  FIG. 18  as an example, the retention number of the current converted file is 1, and the target retention number is 2 on the basis of the result of S 805  to S 807 . Therefore, f calculated in S 850  is 1. Next, the retention number of the current converted file is compared with the target retention number (S 851 ). In the case of determining that the retention number of the current converted file coincides with the target retention number, the retention ratio change determination unit  800 A proceeds to the processing of S 815  (coincidence in S 851 ). In the case of determining that the retention number of the current converted file is smaller (current is smaller in S 851 ), the retention ratio change determination unit  800 A refers to the data structure, statistic information management table  70 A shown in  FIG. 18 , and transmits the load information notification instruction to all the processing computers  21  which store the original file (S 852 ). In the case of determining that the retention number of the current converted file is larger (current is larger in S 851 ), the retention ratio change determination unit  800 A refers to the data structure/statistics information management table  70 A shown in  FIG. 18 , and transmits the load information notification instruction to all the processing computers  21  which store the converted file (S 853 ). The load information of each of the processing computers  21  returned in response to the load information notification instruction transmitted here, and the absolute value f of the difference between the retention number of the current converted file and the target retention number calculated in S 850  are utilized in the data structure conversion method determination processing in  FIG. 28 . 
         [0156]    Next, a description will be given of the data structure conversion method determination processing S 2508  which the data structure conversion method determination unit  900  performs.  FIG. 28  is a flow chart showing an example of the data structure conversion method determination processing S 2508 . The data structure conversion method determination unit  900  selects and determines a method which efficiently performs the retention ratio change of the data structure of the file among the processing computers  21  which instruct all the files determined in S 802  to S 815  to give notification of the load information in any of S 852  and S 853 , in the retention ratio change determination unit  800 A according to the present embodiment shown in  FIG. 27 , and instructs of the method. A description will be given below of the processing by using  FIG. 28 . 
         [0157]    The data structure conversion method determination unit  900  repeats the steps S 901  to S 915 , for all the files on which the retention ratio change determined by the retention ratio change determination unit  800 A according to the present embodiment shown in  FIG. 27  is performed. First, in S 902 , when starting the processing in S 900 , the data structure conversion method determination unit  900  receives all the load information which the retention ratio change determination unit  800 A has instructed each of the processing computers  21 , for the file on which the retention ratio change is performed. The load information received in S 902  corresponds to the load information S 2506  to S 2507  in  FIG. 25 . 
         [0158]    Next, in S 903 , f number of processing computers  21  are selected in the order from the lowest CPU usage rate, by using the value of f which is determined in S 850  of the retention ratio change processing shown in  FIG. 27 , and the information of the CPU usage rate included in the load information of the processing computer  21  received in S 902 . The computer selected here is called an instruction target computer, and the original file or the converted file which is stored therein and is the conversion target is called a conversion target file. Further, a file obtained by applying the data structure conversion processing or the data structure reverse-conversion processing to the conversion target file is called an post-conversion file. Specifically, if the conversion target file is the original file, the post-conversion file is the converted file, and if the conversion target file is the converted file, the post-conversion file is the original file. 
         [0159]    The data structure conversion method determination unit  900  repeats S 904  to S 914  for all the instruction target computers. First, in S 905 , for the conversion target file stored in the instruction target computer, it checks whether or not the post-conversion file is stored in the other computers. The check in S 905  can be performed by referring to the data structure/statistics information management table  70 A shown in  FIG. 18 . In the case of determining that the post-conversion file is stored in the other computers than the instruction target computer, the data structure conversion method determination unit  900  proceeds to the processing in S 906  (existing in S 905 ). On the other hand, in the case of determining that the post-conversion file is not stored in the other computers than the instruction target computer, the data structure conversion method determination unit  900  proceeds to the processing in S 910  (not existing in S 905 ). 
         [0160]    The data structure conversion method determination unit  900  derives the processing  91  to  94  in S 906  on the basis of the load information of the instruction target computer acquired in S 902  and the conversion rule definition file  90  shown in  FIG. 24 . If the derived processing is “conversion”, the data structure conversion method determination unit  900  proceeds to the processing in S 910  (conversion in S 906 ). On the other hand, if the derived processing is “copy”, the data structure conversion method determination unit  900  proceeds to the processing in S 907  (copy in S 906 ). 
         [0161]    At the beginning, a description will be given of the processing S 910  to S 912  performed in the case that the processing derived in the determination in S 906  is “conversion”. The processing flow here corresponds to S 2510  to S 2513  in  FIG. 25 . First, in S 910 , the data structure conversion method determination unit  900  confirms the data structure of the conversion target file. In the case of determining that the data structure of the conversion target file is the original file (original file in S 910 ), the data structure conversion method determination unit  900  instructs the instruction target computer to convert the data structure for converting the data structure of the conversion target file from the original file to the converted file (S 911 ). On the other hand, in the case of determining that the data structure of the conversion target file is the converted file (converted file in S 910 ), the data structure conversion method determination unit  900  instructs the instruction target computer to reverse-convert the data structure for converting the data structure of the conversion target file from the converted file to the original file (S 912 ).  FIG. 25  illustrates the processing in the case of outputting the conversion instruction of the data structure, and the data structure conversion instruction in S 911  corresponds to S 2511  in  FIG. 25 . After outputting any instruction in S 911  and S 912 , the data structure conversion method determination unit  900  proceeds to the processing in S 913 . 
         [0162]    Next, a description will be given of the processing S 907  to S 909  performed in the case that the processing derived by the determination in S 906  is “copy”. The processing flow here corresponds to S 2520  to S 2528  in  FIG. 25 . First, in S 907 , the data structure conversion method determination unit  900  selects one computer which stores the post-conversion file of the conversion target file checked in S 905 . Next, in S 908 , the data structure conversion method determination unit  900  instructs the selected computer to perform data redundancy toward the instruction target computer. The data redundancy instruction here corresponds to S 2521  in  FIG. 25 . The processing computer having received the data redundancy instruction transmits the post-conversion file of the conversion target file toward the instruction target computer. The instruction target computer having received the post-conversion file of the conversion target file performs the data storage processing, and transmits the storage completion notification to the management computer. In S 909 , the management computer receives the storage completion notification, and thereafter gives instruction of the data replacement processing to the instruction target computer. The data replacement instruction here corresponds to S 2526  in  FIG. 25 . Thereafter, the processing proceeds to S 913 . 
         [0163]    The data structure conversion method determination unit  900  ends the processing in S 907  to S 909  or S 910  to S 912 , and thereafter updates the recorded contents of the data structure/statistics information management table  70 A by the most recent information (S 913 ). Thereafter, the processing returns to S 904  and S 901 , repeats the processing loop under a predetermined condition (S 914 , S 915 ), and thereafter ends the processing (S 916 ). 
         [0164]    According to the third embodiment of the present invention described above, the retention ratio of the original file and the converted file can be dynamically changed for further improving the data processing efficiency of the system  10 , by using the statistics information of the analysis request and the load information of each of the processing computers. 
         [0165]    According to the present invention described according to the present embodiments described above, there can be provided the information processing system and the information processing method which can perform the analysis of the semi-structured data at a high speed while maintaining the fault tolerance of the data without having any extra data within the information processing system. 
         [0166]    The description is specifically given on the basis of the present embodiments, but, the present invention is not limited to the present embodiments described above, but can be variously changed within a range which does not deflect from the scope. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           10  Information processing system 
           20  Management computer 
           21  Processing computer 
           24  Storage request computer 
           25  Analysis request computer 
           40  Computer definition file 
           50  Policy definition file 
           60  Analysis request setting file 
           70  Data structure management table 
           70 A Data structure/statistics information management table 
           80  File 
           90  Conversion rule definition file 
           100  Data placement determination unit 
           200  Data redundancy determination unit 
           300  Data structure conversion determination unit 
           400  Analysis request reception unit 
           500  Analysis execution location determination unit 
           600  Data recovery determination unit 
           700  Statistics information recording unit 
           800  Retention ratio change determination unit 
           800 A Retention ratio change determination unit 
           900  Data structure conversion method determination unit 
           1000  Data storage unit 
           1100  Data redundancy unit 
           1200  Data structure conversion unit  1300  Data structure reverse-conversion unit 
           1400  Analysis processing unit 
           1500  Load information notification unit 
           1600  Data replacement unit