# Patent

## Title
System and method for creating a de-duplicated data set

## Abstract

The present invention is directed to a system and method for creating a non-redundant data set from a plurality of data sources. Generally, the system and method operate by creating unique hash keys corresponding to unique data files; compiling the hash keys along with seeking information for the corresponding data files; de-duplicating the hash keys; and retrieving/storing the data files corresponding to the de-duplicated hash keys. Thus, in accordance with the system and method of the present invention, a non-redundant data set can be created from a plurality of data sources. The system of the present invention can operate independently or in conjunction with any de-duplicating methods and systems. For example, a de-duplicating method and system can be used to read and obtain data from a variety of media, regardless of the application used to generate the backup media. The component parts of a file may be read from a medium, including content and metadata pertaining to a file. These pieces of content and metadata may then be stored and associated. To avoid duplication of data, pieces of content and metadata may be compared to previously stored content and metadata. Furthermore, using these same methods and systems the content and metadata of a file may be associated with a location where the file resided. A database which stores these components and allows linking between the various stored components may be particularly useful in implementing embodiments of these methods and systems.

## Background
PRIORITY CLAIM
The present invention claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/287,175 filed on Dec. 16, 2009 and entitled “System And Method For Creating A De-Duplicated Data Set”, the contents of which are incorporated herein by reference and are relied upon here.


RELATED APPLICATIONS
The present application describes a system and method that can operate independently or in conjunction with systems and methods described in pending U.S. application Ser. No. 10/759,599, filed on Jan. 16, 2004, and entitled “System and Method for Data De-Duplication,” which is hereby incorporated herein by reference in its entirety. The contents of U.S. application Ser. No. 10/759,599 are physically incorporated within the description of this application. It should be understood that the system and method of the present application can operate either independently or in conjunction with the systems and methods described in U.S. application Ser. No. 10/759,599.
FIELD OF THE INVENTION
This invention relates generally to extracting data from disparate locales, and more particularly, to methods and systems for extracting and storing data from disparate locales without unnecessary duplication. The present invention most particularly relates to systems and methods for creating non-redundant data sets from a plurality of data sources by employing hashing techniques.
BACKGROUND
Vast amounts of active and archived corporate electronic information exists on backup tape media. Retrieving and collating this data is becoming increasingly important as the information is not only utilized for knowledge management, but may also be the subject of discovery requests by attorneys engaged in litigation involving the corporation. Conventional methods of producing data from large quantities of backup tapes are difficult to implement, cost prohibitive, or both. Managing data from backup media is particularly problematic in the case where companies have many different tape backup systems using different backup environments.
A previous attempt to solve the problem of retrieving information from backup tapes involves restoring the tapes using a “Native Environment” (NE) approach. The NE approach recreates the original backup environment from which the tape was generated so that data from the tapes can be restored and moves the restored data from the replicated environment to a target storage system for further analysis.
Replicating the NE in order to restore backup tapes requires that all server names, configurations, software versions, user names, and passwords are consistent with the environment as it stood at the time of the backup. Replicating all of this information becomes quite challenging as systems age, names of systems change, passwords change, software versions change, and administrators change. Furthermore, backup software is typically designed to restore data for the purposes of disaster recovery (an all or nothing proposition) and not to intelligently process large amounts of data from large numbers of media to obtain only relevant information.
Even if the backup environment can be recreated, however, all the records may need to be examined. Those records may contain information regarding thousands of employees in the case of a large company. Managing all this data is a nightmare, even if the environment can be recreated. For many companies, the amount of information can exceed a terabyte. Storing over a terabyte of information takes a great deal of memory space and consumes valuable computer resources during the storing operation.
Beyond trying to manage the sheer volume of data, other problems exist. Most backup systems retrieve data for backup on a regular schedule, however, this means that with every successive backup much of the data saved is a duplicate of data saved during the previous backup. This is especially problematic as data sensitivity increases, as backup frequency usually increases commensurately with data sensitivity. Additionally, though the data itself may be duplicative, the location where this duplicative data is found may be different, and the location where the data resides may be of importance as well. As, for example, when this data must be restored to its original locale.
Thus there is a need for systems and methods to store and collate data from disparate locales which retains the location of various pieces of data without duplicating identical data.
Conventional de-duplication systems generally aim to take a duplicated set of data and remove duplicate entries. This is generally performed by having a single central system traverse all of the data in the duplicated data set. While traversing the duplicated data set, the system through some means, generally a hashing means, attempts to characterize the data in some unique manner (e.g. hash value). As is well known, a hash function is any well-defined procedure or function that converts a large, possibly variable-sized amount of data into a small datum, usually a single integer that may serve as an index to an array. The system then generally creates a unique list of data by maintaining a list of unique hash values. When the system encounters a data item whose hash value already exists in the system, the system deletes the data item corresponding to that hash value as it is considered to be duplicate data. This type of system is not entirely advantageous as such systems only utilize a single node to traverse all of the data, which can be taxing and slow.
SUMMARY
Systems and methods for extracting files from various media and storing these files without duplicating identical components of the file are disclosed. These systems and methods may read the components of a file, including the file's content and metadata, from a media. The extracted content and metadata components of the file may then be compared against previously stored content and metadata to insure that the duplicate storage of content or metadata does not occur.
In one embodiment, components of a file are read including the content and metadata of a file, the content is compared with previously stored content and stored if substantially identical content is not found. The metadata is then compared to previously stored metadata and stored if substantially identical metadata is not found. The stored metadata is associated with the substantially identical content if it was found, and the stored content if substantially identical content was not found.
In some embodiments, the components of a file include the location of the file.
In similar embodiments, the location is compared to previously stored locations and stored or associated accordingly.
In yet other embodiments, content and metadata may be compared by generating a digital signature, and comparing this digital signature with previously stored digital signatures.
In another embodiment, the digital signature is generated using the SHA1 hashing algorithm.
Additionally, systems and apparatuses are presented which embody these methodologies in computer systems, hardware, and software.
The present invention is directed to a de-duplication system and method for creating a non-redundant data set from one or more data sources.
In accordance with one aspect of the invention, the present system and method includes a high-speed de-duplication system, comprising one or more pods in communication with a database system and a consolidated storage system.
A pod is any general computing system (one or more processors, a module or group of network computer, storage, and application components that work together to a deliver a network service) that can perform various tasks associated with file handling such as, data traversal and hashing. Data is stored and processed by the pods (one or more) in any number of formats. Further, data is associated with a particular custodian and is stored accordingly. For example, in an exchange environment, email messages are typically stored in custodian mailboxes, which can be produced as PST files (Personal Storage Table, an open proprietary file format used to store data within Microsoft software such as Microsoft exchange client, Windows Messaging, and Microsoft Outlook) from EDB files (Database files of the Exchange Server). Other types of data files associated with a particular custodian are stored in what here is referred to as a custodian container. A custodian container is a file that contains files associated with a custodian. For example, a PST file or ZIP file (data compression or archive format) are suitable custodian containers. Alternatively, a custodian container is a collection of files that can be commonly accessed or a logical grouping of files associated with a custodian.
Generally, the database system is configured similar to any database system that is adapted to access external text files via Simple Query Language SQL (or variants) as though they are actual tables in the schema. The database system communicates with the pods and the storage system and processes information regarding the data on the pods. The storage system connected to the database system and pods is a centralized or distributed storage system that can be centrally identified, consolidated and addressed. The storage system is adapted to be accessed by the pods and database system.
In accordance with another aspect of the invention, a method is provided for creating a new data set that eliminates data redundancy from a plurality of data sources. The de-duplication method may be performed globally or on a custodian-by-custodian basis. When the method is performed globally, a single new data set is created from the existing sets of data. When the method is performed on a custodian-by-custodian basis, new separate data sets are created for each custodian from the existing sets of data.
In a preferred implementation of the present invention, the de-duplication method comprises three phases. Generally, in the first phase, each pod traverses the data files contained in a custodian container and creates indices of the custodian container in the storage system. The indices contain hash keys representing the data files and “seek” information for locating and handling the data files. In Phase II, the database system 300 creates a Master Key table of unique hash keys and seeks information from all the data indices created in Phase I. In Phase III, the pods query the database system's Master Key table of unique hash keys and, using the “seek” information, produce the data files associated with the hash keys to the storage system.
Phase II may be performed before the first phase is completed for all custodian containers (i.e., the Phase II may be performed once Phase I is completed for a just a single custodian container). Phase III may begin on a pod once Phase I is complete for all custodian containers on that pod and Phase II is complete for at least a single custodian container on that pod. Thus, although the commencement of the three phases is staggered, Phase I and Phase II are performed in parallel.
These, and other, aspects of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. A reader should be understood, however, that the following description, while indicating various embodiments of the invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many substitutions, modifications, additions or rearrangements may be made within the scope of the invention, and the invention includes all such substitutions, modifications, additions or rearrangements.



BRIEF DESCRIPTION OF THE DRAWINGS
In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Specifically, FIGS. 4-10 depict one particular embodiment for accomplishing a de-duplication operation; it should be understood that the present system and method may operate independently or in conjunction with this particular operation. Also, it should be understood that these drawings depict only typical embodiments of the invention and therefore, should not be considered to be limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
FIG. 1 is a diagram a de-duplication system in accordance with an exemplary embodiment of the invention;
FIG. 2 is a timing diagram illustrating an exemplary implementation of a global de-duplication method in accordance with the invention; and
FIG. 3 is a flow diagram illustrating an exemplary implementation of a de-duplication method in accordance with the invention.
FIG. 4 includes an illustration of a computing system used to obtain data from a backup medium using a non-native environment in accordance with one particular embodiment for performing de-duplication.
FIG. 5 includes an illustration of a database layout in keeping with the one particular embodiment for performing de-duplication.
FIG. 6 includes a process flow diagram for extracting data from disparate locales without unnecessary duplication.
FIGS. 7-10 illustrate examples in keeping with embodiments for performing de-duplication.



DETAILED DESCRIPTION
The invention and the various features and advantageous details thereof are explained more fully with reference to the nonlimiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well known starting materials, processing techniques, components and equipment are omitted so as not to unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while disclosing preferred embodiments of the invention, are given by way of illustration only and not by way of limitation. Various substitutions, modifications, additions and/or rearrangements within the spirit and/or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure.
Various embodiments of the invention are described in detail below. While specific implementations involving electronic devices (e.g., computers) are described, it should be understood that the description here of those implementations is merely illustrative and not intended to limit the scope of the various aspects of the invention. A person skilled in the relevant art will recognize that other components and configurations of the electronic devices may be easily used or substituted than those that are described here without parting from the spirit and scope of the invention.
Moreover, those skilled in the art will appreciate that the invention may be practiced with any number of computer system configurations (one or more) including, but not limited to, distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. The present invention may also be practiced in and/or with personal computers (PCs), hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like.
The present invention is directed to a de-duplication system 100 and method for creating a non-redundant data set from one or more data sources. Creation of a non-redundant data set may be advantageous in various contexts. For example, in data migration, creating a non-redundant data set provides more efficient use of computing resources. Also, in electronic discovery for litigation, creating a non-redundant data set allows more efficient review and processing of the data. The present invention allows creation of a non-redundant data set from data that may be stored in one or more disparate locales. For example, data to be de-duplicated may reside on backup tapes, disk drives, and/or other suitable storage means. In these various storage means, data may be associated with a particular custodian and may be stored accordingly. For example, in an exchange environment, email messages may be stored in custodian mailboxes which can be produced as PST files from EDB files. Other types of data files associated with a particular custodian may be stored in what herein is referred to as a custodian container. A custodian container may be a file that contains data files associated with a custodian. For example, a PST file or ZIP file may be suitable custodian containers. Alternatively, a custodian container may be a collection of files that can be commonly accessed, or a logical grouping of files associated with a custodian.
In accordance with one aspect of the invention, a data-agnostic, high-speed de-duplication system 100 is provided. As shown in FIG. 1, the de-duplication system 100 of the present invention comprises one or more pods indicated by reference numeral 200 in communication with a database system 300 and a consolidated storage system 400. Data is collected and conveyed on a connection to the pods 200 and the database system 300. The de-duplication system 100 can operate either in a heterogeneous distributed network environment or in a homogenous distributed network environment.
In a preferred embodiment, a pod 200 is any general computing system that can perform various tasks associated with file handling such as, data traversal and hashing. Although, in the preferred embodiment, all of these functions are performed preferably by a pod 200, in other embodiments, these functions can be performed by separate, additional components in the de-duplication system 100. The pods 200 are conventional work stations and/or servers, though they can be any system, virtual or physical. The data stored and processed by the pods 200 can be in any number of formats. For example, the data stored on a pod 200 can be an EDB file from which PST files can be generated, each PST file corresponding to a custodian mailbox. Also, the data can be in loose files associated with a particular custodian and stored in a custodian container.
Generally, the database system 300 can be any database system that is adapted to access external text files via Simple Query Language SQL (or variants) as though they are actual tables in the schema. For example, the database system 300 can be an Oracle database with the AV 3.2 schema. The database system 300 communicates with the pods 200 and attached storage 400 on the system 100 and processes information regarding the data files stored on the pods 200 to create a table of non-redundant data files.
The storage system 400 connected to the database system 200 and pods 300 can be a centralized or distributed storage system that can be centrally identified, consolidated and addressed. The storage system 400 is adapted to be accessed by all the pods 200 and database system 300 such that all addressing is invariant of the computing system accessing the storage.
In accordance with another aspect of the invention, a method is provided for creating a new data set that eliminates any data redundancy from one or more data sources. The de-duplication method can be performed globally or on a custodian-by-custodian basis. When the method is performed globally, a single new data set is created from the existing sets of data. When the method is performed on a custodian-by-custodian basis, new separate data sets are created for each custodian from the existing sets of data.
In a preferred implementation, the de-duplication method comprises three phases of operations. Generally, in Phase I, each pod 200 operates to serially process the custodian containers on a pod 200 by traversing the data files contained in each custodian container and creating separate indices for each custodian container. The indices contain hash keys representing the data files and seek information for locating and handling the data files. In Phase II, the database system creates a Master Key table of unique hash keys and seeks information from all the data indices created in Phase I operations. In Phase III operations, the pods 200 query the database system's Master Key table of unique hash keys and, using the seek information, produce the data files associated with the hash keys to the storage system. A more detailed description of the above-referenced three phases with reference to FIGS. 2 and 3 is set forth below.
Phase II operations may be performed before the first phase is completed for all the custodian containers (i.e. the Phase II may be performed once Phase I is completed for a just a single custodian container). Phase III may begin on a pod once Phase I is complete for all custodian containers on that pod and Phase II is complete for at least a single custodian container on that pod. Thus, although the commencement of the three phases is staggered, Phase I and Phase II are performed in parallel. FIGS. 2 and 3 illustrate exemplary implementations of these three phases.
Phase I
In Phase I, the pods 200 in the system 100 conduct a traversal of all data stored on the pods 200. Preferably, each pod traverses its data on a custodian-by-custodian basis serially; however, multiple pods 200 may process multiple custodian containers in parallel. During this traversal, each data file within a custodian container is inspected and hashed. Generally, hashing refers to the creation of a unique value (“hash key”) based on the contents of a data file. A preferred exemplary hashing process is fully disclosed in U.S. patent application Ser. No. 10/759,599, filed on Jan. 16, 2004, and entitled “System and Method for Data De-Duplication (RENEW1120-3), which is incorporated by reference herein in it entirety. In a preferred implementation, each hash key generated for a data file is a SHA1 type hash.
Also, upon initiation of Phase I, for each custodian container stored on a pod, the pod creates 256 text files (also referred to as “buckets”). The text files are preferably created on the storage system 400. Each text file or bucket is named with a unique identifier. The unique bucket identifier comprises a custodian container ID and first byte of a hash key (i.e. 00 through FF in Hex). When a hash key is generated, it is placed in its corresponding bucket. For example, for a given custodian container, a hash key beginning with 1E will be placed into that custodian container's 1E bucket.
Additionally, in Phase I, the pods preferably acquire seek information for each of the data files so that the data files can later be found without conducting another full traversal of the data and can be easily accessed with the proper tools required for extraction. When a hash key representing a particular data file is entered into a text file/bucket, seek information for the data file may also be entered into the text file/bucket and associated with the data file's hash key.
Once a custodian container has completed Phase I processing by a pod 200, the system 100 indicates that the 256 text files/buckets corresponding to the custodian container are finished with Phase I or Phase I complete. For example, pod 200 may indicate completion of Phase I with respect to a custodian container by making an entry into an event status table, which may be stored on the database 300 or storage system 400.
In an exemplary implementation of Phase I with respect to email message data, one or more EDB files may be stored on a pod 200. When Phase I operation is initiated, each pod 200 creates 256 text files (numbered 00 through FF) for each custodian container (i.e. PST file) generated from the EDB's. Preferably, all of the pods 200 create the text files on the storage system 400. The pods 200 may preferably start by processing 50 of their custodian containers (i.e. PST files). Operation of system 100 has been demonstrated for 60 pods, each processing 50 PST files. Neither the number of PST files, nor the number of pods, that are processed serve as a theoretical limit, but are simply a current hardware constraint. The pods 200 go through every item in every PST file and create a hash key which is recorded in the corresponding text file/bucket along with seek information used to locate and retrieve the data again. When a PST file is completely processed, the pod 200 provides some indication that the 256 text files/buckets corresponding to a custodian container (i.e. PST file) are ready for Phase II operation. For example, pod 200 may indicate completion of Phase I with respect to a custodian container by making an entry into an event status table, which may be on the database 300 or storage system 400.
Phase II
In Phase II, the database system 300 processes text files/buckets corresponding to multiple custodian containers generated across different pods 200. Preferably, each pod 200 stores its text files/buckets on the storage system 400 such that the database system 300 has easy access to all of the hash key data it requires for de-duplication. In Phase II, as many Phase II ready text files/buckets as possible are processed (up to a configurable cap).
Preferably, the database system 300 can logically address the text files/buckets created as logical addressable DB tables that can be queried by the database system 300 using SQL. Thus, the database system 300 can query the text files/buckets as though they were part of the local database system. Alternatively, the text files/buckets might be database files themselves, but the computational loads would be slightly altered and extra licenses might need to be purchased depending on the system chosen. For each custodian container, the database system 300 assigns external tables to the text files/buckets. Once this assignment is complete, the database system 300 can access these text files/buckets via SQL as though they are actual tables in the schema.
In Phase II, once all of the text files/buckets corresponding to a custodian container are assigned, the database system 300 processes the hash keys in the text files/buckets and begins compiling a Master Key table of unique hash keys and corresponding seek information. Preferably, the database system 300 may conduct Phase II by processing all available custodian containers' “00” bucket, then moving on to the custodian containers' “01” bucket, and so forth consecutively through all the buckets. Alternatively, the buckets may be processed in reverse order (i.e. FF to 00) or in random order. The Master Key table is a database table that is created by the database system 300 by reading all of the hash keys from the buckets and adding entries to the Master Key table only when the hash keys are not already in the Master Key table. Thus, the Master Key comprises only unique hash keys and corresponding unique seek information. Once all of the buckets corresponding to a custodian container are Phase II complete, the system 100 provides some indication that the custodian container is Phase III ready. For example, an entry indicating that a bucket is Phase III ready may be made into an event status table located on the database 300 or storage system 400.
Phase III
Pods 200 periodically check the event status table to see whether any custodian containers are Phase III ready. Once a pod 200 sees that one of its custodian containers is Phase III ready, the pod will query the Master Key table for hash keys corresponding to the pod's custodian containers. Each pod 200 fetches data files/items associated with hash keys in the Master Key table that correspond to that pod's custodian containers and adds them to a specified location on the storage system 400. The pods 200 go through the Master Key table and use the seek information to identify where the data is located and how to extract the data. The seek information may include specifying plugins to handle specific data types, such as information regarding extraction of PST files out of EDB files.
Additionally, the system 100 and method of the present invention may track multiple occurrences of hash keys, such that the pods 200 can find additional seek information for hash keys that correspond to identical data files that reside in a plurality of file locations.
FIG. 2 illustrates an exemplary implementation of Phases I-III in accordance with the foregoing description of the present invention. FIG. 2 illustrates the processing of two pods, each having three custodian containers. The custodian containers in the first pod are from a first EDB file and the custodian containers in the second pod are from a second EDB file, which is a more current backup of the same mail server. Although FIG. 2 shows only two pods and six custodian containers, a person skilled in the art will recognize that the disclosed system and method may be implemented with more pods and custodian containers to further exploit the advantages of the present invention.
Although the above description may contain specific details, they should not be construed as limiting the claims in any way. Other configurations of the described embodiments of the invention are part of the scope of this invention. In addition, one particular embodiment for performing de-duplication is described below. The system described above with respect to FIGS. 1-3, can operate either independently or in conjunction with the system and methods or any aspects thereof described below with reference to FIGS. 4-10.
A few terms are defined or clarified to aid in understanding the descriptions that follow. As used in this specification, a file may consist of one or more components, these components can include the contents, metadata, and location of a file. The contents may be the string of bytes or information that make up the file, the metadata may be information pertaining to a variety of aspects of the file such as the file name, date of creation, date of last modification, length, etc., and the location of the file may refer to the volume or source container where the file was originally stored. A file in this context may refer to any string of bits or electronic asset, such as programs, text, directory, data, email and/or their respective components or any subset thereof.
Media may refer to any medium, whether it is backup tapes, CD ROM, hard disk or any similar storage media. Initially, files may reside on any number of different mediums operating on different platforms. Files may also be located on backup tapes created from any number of different backup systems and strategies. However, media may also refer to the original storage location of these files. Original data refers to files as they exist before they accessed by embodiments of the present invention, whether extant on backup media or in active use.
The methods and systems described in more detail below can be used to extract data directly from media to a target location without the replication of duplicate data. The increased speed and efficiency allowed by these systems and methods allow previously cost prohibitive data production jobs to be performed within reasonable cost and time parameters. By ameliorating the problems involved with the duplication of data, these methods and systems also decrease the expense of hardware used to implement the database which stores extracted data.
Furthermore, the location of duplicate data may be stored within the same database without the storage of the duplicate data itself. A suite of software applications can be used to extract data from any environment, any operating system, basically any host platforms and any backup system tape while simultaneously retaining information on the location of the data and filtering duplicative information. These capabilities significantly curtail the amount of storage required for the data extracted by ensuring that duplicate data is. not stored in the database.
Before discussing embodiments of the present invention, an exemplary hardware and software architecture for using embodiments of the present invention is described. FIG. 4 illustrates such an exemplary hardware architecture and includes network 142A. Bi-directionally coupled to the network 142A are server computer 122A, enterprise database 124A, client computer 126A, backup media 128A, and database server computer 152A. Database server computer 152A may be coupled to database 160A. Database 160A may be coupled to a persistent storage medium 182A, such as an optical storage or tape drive, and input/output device (“I/O”) 184A, such as a printer or monitor.
Database 160A may allow the contents of a file to be associated with metadata and locations pertaining to the file, furthermore database 160A may allow stored content to be associated with multiple locations and pieces of stored metadata, stored metadata to be associated with multiple locations and pieces of stored content, and stored locations to be associated with multiple pieces of stored metadata and content. In one embodiment, database 160A may be a single depository that has the ability to store and relate the contents, metadata, or location of a file extracted from server computer 122A, enterprise database 124A, client computer 126A, or backup media 128A.
FIG. 5 depicts the layout of one embodiment of such a database 160A. File 228A, originally resident at location C:\user\file.txt 226A, may be stored in database 160A as three separate components, content 222A of file 228A, metadata 224A pertaining to file 228A, and original location of file 226A. Hash tables 240A, 230A, 210A of the type commonly known in the art are used to contain file location data 226A, metadata 224A, and content 222A respectively. In many embodiments, components 222A, 224A, 226A of file 228A are linked together in database 160A to facilitate reconstruction of file 228A and to avoid the storage of duplicative content 222A and metadata 224A as described later.
In one embodiment, when file 228A is extracted from location 226A, content 222A and metadata 224A portions of file 228A may be defined. Content 222A, metadata 224A, and location 226A of file 228A will then be hashed to generate substantially unique hash values 214A, 234A, 244A. The resulting digital signatures 214A, 234A, 244A will be used as index values into the corresponding hash tables 210A, 230A, 240A. For example, content 222A may hash to the value of 125A (214A), this value 214A may in turn serve as an index into content hash table 210A, and the entry 212A in content hash table 210 corresponding to hash value 214 may contain the original content 222A of file 228A. Additionally, entry 212A in content hash table 210A may contain links 216A, 218A to associated locations 226A or metadata 224A of file 228A or possible other locations and metadata associated with content 222A. In some embodiments, these links 216A, 218A may be the hash values 244A, 234A of location 226A, and metadata 224A; these hash values 244A, 234A serve as indexes into location and metadata hash tables 240A, 230A as described below.
Similarly, metadata 224A and location 226A of file 228A may be hashed to generate substantially unique digital signatures 234A, 244A. These signatures 234A, 244A may then serve as index values into metadata and location hash tables 230A, 240A respectively. Additionally, entries in metadata hash table 230A may contain links 236A, 238A to location 226A and content 222A corresponding to file 228A, while entries in location hash table 240A may contain links 246A, 248A to content 222A and metadata 224A corresponding to file 228A. These links 236A, 238A, 246A, 248A may consist of the associated digital signature for the location 226A, content 222A, and metadata 224A. In this manner file 228A may be stored in database 160A and reconstituted at will, additionally access to any component 222A, 224A, 226A of file 222A in database 160A will allow access to any other component of file 222A as will be apparent to one of ordinary Skill in the art. It will also be apparent that these same structures may be used to store and link as many or as few components or pieces of information as is desired. An exemplary embodiment of database 160A is illustrated in Example 1.
Returning to the structure of FIG. 4 momentarily, additional server computers (similar to server computer 122A), enterprise databases (similar, to enterprise database 124A), client computers (similar to client computer 126A), and backup media (similar to backup media 128A) may be bi-directionally coupled to network 142A but are not shown in FIG. 4. An example of client computer 126A may include a desktop computer, a laptop computer, a personal digital assistant, a cellular phone, a workstation, or nearly other device capable of communicating over network 142A.
Although not shown, each database 124A may include a database server computer used to process instructions sent over network 142A to its corresponding database. Database 160A may be coupled to many other devices in addition to or instead of persistent storage medium 182A and I/O 184A.
Each of the computers may comprise a central processing unit (“CPU”), a read-only memory (“ROM”), a random access memory (“RAM”), a hard drive (“HD”) or storage memory, and I/Os. I/Os can include a keyboard, monitor, printer, electronic pointing device (e.g., mouse, trackball, stylus, etc.), or the like. Additionally each of the computers in FIG. 4 may have more than one CPU, ROM, RAM, HD, I/O, or other hardware components. Note that FIG. 4 is a simplification of an exemplary hardware configuration. Many other alternative hardware configurations are possible and known to skilled artisans.
Each of the computers in FIG. 4 is an example of a data processing system. ROM, RAM, and HD can include media that can be read by the CPUs. Therefore, each of these types of memories includes a data processing system readable medium. These memories may be internal or external to the computers.
Portions of the methods described herein may be implemented in suitable software code that may reside within ROM, RAM, or a hard disk. The instructions in an embodiment of the present invention may be contained on a data storage device, such as a hard disk. FIG. 5 illustrates a combination of software code elements 204A, 206A, and 208A that are embodied within a data processing system readable medium 202A, on HD 200A. Alternatively, the instructions may be stored as software code elements on a DASD array, magnetic tape, floppy diskette, optical storage device, or other appropriate data processing system readable medium or storage device.
In an illustrative embodiment of the invention, the computer-executable instructions may be lines of assembly code, compiled C, C++, Java, or other language code. Other architectures may be used. For example, the functions of any one of the computers may be performed by a different computer shown in FIG. 4. Additionally, a computer program or its software components with such code may be embodied in more than one data processing system readable medium in more than one computer.
In the hardware configuration above, the various software components may reside on a single computer or on any combination of separate computers. In alternative embodiments, some or all of the software components may reside on the same computer. For example, one or more the software component (s) of server computer 122A could reside on client computer 126A, a database server computer 152A, or any combination thereof.
Communications between any of the computers in FIG. 4 can be accomplished using electronic, optical, radio-frequency, or other signals. For example, when a user is at client computer 126A, client computer 126A may convert the signals to a human understandable form when sending a communication to the user and may convert input from a human to appropriate electronic, optical, radio-frequency, or other signals to be used by, a database server computer. Similarly, when an operator is at database server computer 152A, the database server computer 152A may convert the signals to a human understandable form when sending a communication to the operator and may convert input from a human to appropriate electronic, optical, radio-frequency, or other signals to be used by any of the computers.
Attention is now directed to systems and methods to place the electronic information (or data) from back-up storage devices (e.g., tapes, such as tapes 144A), network devices (e.g., servers, such as server 122A) or other media onto a storage medium which may include a database (e.g., database 160A) and to apply a retention policy to the information (prior to, concurrently with, or after the information has been placed on database 160A) so that the information remaining in database 160A is only information that meets the criteria of the retention policy. The database 160A may be populated from historical back-up data. The collection of information to populate the database 160A can include a de-duplication step to ensure database 160A does not contain duplicate copies of content.
These methods and systems can involve taking data (email, text, etc.) directly from the backup media 162A, 166A and storing it to a database, which may reside on hard disk 164A. FIG. 6 illustrates one method for extracting data from a backup medium and storing it to a database without storing duplicative components.
In one embodiment, as illustrated in the flow chart of FIG. 6, the method can comprise communicating with the hardware (e.g., understand the stored data formats/hardware protocols (e.g., SCSI) in order to read the raw data) to read a file (block 302A), discerning the respective content and metadata of the extracted file (block 312A), comparing the content of the extracted file with the previously stored content (block 322A), and if substantially identical content is not found during this comparison, storing the content (block 342A)) next comparing the metadata of the file with previously stored metadata (block 362A) and storing the metadata if substantially identical metadata is not found (block 382A), metadata and content can then be associated based upon the presence or absence of identical previously stored content or metadata (block 392A).
Note that not all of the activities described in the process flow diagram are required, that an element within a specific activity may not be required, and that further activities may be performed in addition to those illustrated, Additionally, the order in which each of the activities are listed is not necessarily the order in which they are performed. After reading this specification, a person of ordinary skill in the art will be capable of determining which activities orderings best suit any particular objective.
In one embodiment, the methods and systems of the present invention may include reading files from various data sources 122A, 124A, 126A, 128A, 144A (block 302A in FIG. 6). When archiving data from a variety of sources the initial step is to extract a file from a medium (block 302A). Generally speaking, communication with hardware is done according to a specification for the hardware devices (e.g., the SCSI protocol for SCSI devices). In order to read the raw data from a medium, the system needs to recognize the type of device (i.e., reading from a SCSI storage device) on which the data is stored in order to understand the protocol that allows reading the data directly from the device. Thus, the communication with the hardware and reading the raw data directly requires identifying what type of device is being accessed (e.g., a SCSI device, a fiber channel device, etc.), and then based on the protocols for that particular device (e.g., SCSI, iSCSI, fiber channel, etc.), utilizing a software program that will go in and read the data directly from that device.
In order to develop the program for a particular protocol, a programmer would need to review protocol and understand to a certain degree the protocol in order to write a program that will extract the data from that type of protocol device directly. While there may be nuances about each different protocol (e.g., how you do it for a SCSI device may not be the same as how you it for a fiber channel device, etc), skilled artisans understand the protocols, and therefore, the process of extracting or reading these files will be apparent.
In order to do get access to the information on a backup tape, in one embodiment, the method can comprise communicating with the hardware to read a file (block 302A). This communication may identify parameters used for conventional back systems, include the backup system used for a particular backup tape, the protocol used for the backup, notations for determining how individual files and other records are stored on the tape, and the like. By knowing that information, the database server computer 152A can determine the data structure of a backup tape without having to recreate the environment of the conventional backup system. Reading a file (block 302A) from conventional backup tapes 144A can further comprise transferring original data from backup tape without recreating the native environment. Because database server 152A can be configured to understand the format of the information on the tape, the database server 152A can import the data in a form that is more easily and accurately managed.
In many instances, the information used to identify the backup application can be located in the first portion of the tape. In another embodiment the information may be at a different location(s), thus other portion(s) of the tape may be read. In still another embodiment, the entire tape may be read before starting to interpret or reverse engineer data from the tape. These other embodiments may be useful if the identifying signature of a tape or file would lie at an unconventional location (near the end of the tape or buried in between). Files may also be read (block 302A) over network 142A from a variety of different sources including file systems resident on server and network computers not depicted.
However, not all files read (block 302A) will necessarily need to be stored because many copies of an electronic file, electronic mail message, database record, or other electronic data may exist on many different computers or on backup tapes. In order to avoid this needless duplication of data, after a file is read (block 302A) the file may be separated into its respective content and metadata (block 312A), and these components compared to components already resident in database 160A.
Database server 152A reads the content and obtains the corresponding file metadata. There may be a certain degree of overlap between components of a file, and database server may segregate content and metadata according to a variety of different circumstances and conventions which will be obvious to one of ordinary skill in the art. For a file, the metadata portion may include an Internet Protocol address or other address of a computer from which the file is obtained. Additional metadata pertaining to a file may include the file path and filename, date the file was last saved on that particular computer, a pointer to the content portion within that computer, size of the file, create, access, and modify dates, file type, owner/access information and the like.
After the metadata is separated from the content of a file (block 312A) the content may be compared against the content previously extracted and already resident in database 160A (block 322A). Comparing the content to previously extracted content may involve creating a digital signature from the content of the extracted file, and comparing this digital signature to the digital signature of content from previously extracted files, In particular embodiments of the invention this comparison may involve creating a digital signature by hashing at least a portion of the content of the extracted file to form hashed values.
These hash algorithms, when run on content produce a unique value such that if any change (e.g., if one bit or byte or one change of one letter from upper case to lower case) occurs, there is a different hash value (and consequently digital signature) for that changed content. This uniqueness is somewhat dependent on the length of the hash values, and as apparent to one of ordinary skill in the art, these lengths should be sufficiently large to reduce the likelihood that two files with different content portions would hash to identical values, When assigning a hash value to the content of an extracted file, the actual stream of bytes that make up the content may be used as the input to the hashing algorithm. The hashed values may also be used for storing data within database 160A, as described above.
In one embodiment, the hash algorithm may be the SHA1 secure hash algorithm number one—a 160-bit hash. In other embodiments, more or fewer bits may be used as appropriate. A lower number of its may incrementally reduce the processing time, however, the likelihood that different content portions of two different files may be improperly detected has being the same content portion increases. After reading this specification, skilled artisans may choose the length of the hashed value according to the desires of their particular enterprise.
After hashing the content to create a digital signature, this digital signature may be used to compare the content of the extracted file to content of previously extracted file resident in database 160A (block 322A). As described, database 160A may utilize a hash table to store the content of a file and the corresponding digital signature of that content. Thus, for each piece of content stored, the primary key into the hash table may be the hash value of that content.
Consequently, to compare the content of the extracted file to content already resident in database 160A (block 322A) the hashed value of the content is compared to the hashed values contained in content hash table 210A for existing content in database 160A. If the hash value is not identical to any previously stored hash values, this indicates that content identical to the content of the extracted file is not resident in database 160A. In this case, the content of the extracted file may be stored in database 160A (block 342A). In associated embodiments, the location from which the file was extracted is linked to the content of the extracted file in database 160A.
Conversely, if during this comparison (block 322A) the hash value is identical to a previously stored hash value in content hash table 210A, content identical to the content of the extracted file is already present in database 160A. In this case, there is no need to store the content of the extracted file, as identical content is already present in database 160A. In certain embodiments, there may be rules which specify when to store content regardless of the presence of identical content in database 160A. For example, a rule may exist that dictates that if content is part of an email attachment to store this content regardless whether identical content is found in database 160A during this comparison (block 322A). Additionally, these type of rules may dictate that all duplicative content is to be stored unless it meets certain criteria.
However, it may be that not only do two files exist with the same content, but additionally that two files have the same metadata as well (e.g. the same file backed up on two separate occurrences). Embodiments of the invention may alleviate the need to store repetitive metadata by comparing the metadata of the extracted file with metadata previously stored in database 160A (block 362A). This comparison (block 362A) may be accomplished in substantially the same manner that the comparison of content is achieved. The metadata of the extracted file is hashed, this hash value is compared to the hash values of previously stored metadata in metadata hash table 230A of database 160A. When hashing the metadata, a stream of metadata may be used as input to the hashing algorithm. For example, using a simple case, suppose the extracted file is named “FILE.TXT” with a last modified data of 1/14/2003 at 4:20 PM, then an ASCII string such as “FILE.TXT|01-14-2003|16:20:00” may be used as input to the hashing algorithm to create a hash value for the metadata.
If a match is not found for this hash value in database 160A the metadata may be stored in database 160A (block 382A). The location from which the file corresponding to the metadata was extracted may also be stored and associated with the metadata. If, however, a match is found, this indicates that identical metadata is already present in database 160A. As with the content of a file, there may be rules which specify when to store metadata regardless of the presence of identical metadata in database 160A. For example, a rule may exist that dictates that if metadata pertains to an email attachment to store this metadata regardless whether identical metadata is found in database 160. Additionally, these type of rules may dictate that all duplicative metadata is to be stored unless it meets certain criteria.
Once it is determined if identical content and metadata are present in database 160A, these newly stored and previously stored pieces of content and metadata may be associated depending on the presence or absence of identical pieces of content and metadata. In most cases, four distinct scenarios nay occur: 1) identical content and metadata were already present in database 160A. The presence of both identical content and metadata indicates that there is no need to store either the content or the metadata of the extracted file, only to verify that these identical pieces of content and metadata are associated in database 160A. 2) If identical content was present but identical metadata was not, the newly stored metadata of the extracted file may be associated with the previously stored identical content, creating a representation of the file in database 160A. 3) The converse is true if identical metadata was present but identical content was not; the newly stored content of the extracted file may be associated with the previously stored identical metadata; and 4) if neither identical content nor identical metadata is found in database 160A the newly stored content and metadata of the extracted file may be associated.
Under any of these circumstances, the location of the extracted file may also be compared to a table of locations currently associated with the stored metadata and content. Similarly to the above operations, if an identical location is found, it may be verified that this location is associated with content and metadata (either previously or newly stored) pertaining to the extracted file, If the location of the extracted file is not present in database 160A it may be stored and appropriately associated with content or metadata (either previously or newly stored) pertaining to the extracted file.
As mentioned above, the steps in FIG. 6 may be preformed in any order, and steps may be added or removed as desired. For example, it would be obvious to those of skill in the art that metadata from the extracted file may be compared to previously stored metadata in database 160A before content from the extracted file is compared. In certain instances the presence or absence of this metadata may in and of itself indicate the presence or absence of identical content in database 160A, just as the presence or absence of identical content in database 160A may indicate the presence or absence of identical metadata. In many of these cases the comparing, storing, and associating of these redundant components of a file may be obviated, or may occur with a reduction in steps.
EXAMPLE
Specific embodiments of the invention will now be further described by the following, nonlimiting example which will serve to illustrate in some detail various features. The following examples are included to facilitate an understanding of ways in which the invention may be practiced. Readers will appreciate that the examples which follow represent embodiments discovered to function well in the practice of the invention, and thus can be considered to constitute preferred modes for the practice of the invention. However, many changes can be made in the exemplary embodiments which are disclosed while still obtaining like or similar result without departing from the scope of the invention. Accordingly, the example should not be construed as limiting the scope of the invention.
Example 1
The following tables illustrates a database which may be used to store and link various components of an extracted file.
1.2) Design Considerations:
a) Metadata from files, directories, e-mail messages may be used to generate unique ID'S for tables. The ID will be generated by combining metadata and using the RFC 3174 algorithm to produce a 160 bits hash value. The 160-bit key will be grouped in 4-bit hexadecimal numbers producing a 40-characters hexadecimal value.
b) The database may be designed to run on a Microsoft SQL Server DBMS
2) Database Tables
2.1) Table prdSource
This table contains information regarding the source of the data (tape, hard drive, file system, etc.)
The primary key for this table is a four bytes (integer) field named SourcelD. This field is auto generated by the database.
Fields:













Name
Type
Size
Comments


















SourceID
Int
4
Not null, autonumber, unique


Type
Char
20
Not Null, (tape, hard drive, file





system)


CreateDate
Datetime
8
Allows null


ModifyDate
Datetime
8
Allows null


AccessType
Datetime
8
Allows null


Attributes
Varchar
50.
Allows null


VolumeName
Varchar
256
Allows null


JobNo
Varchar
16
Not Null, required, Renew Data Job





Number


MediaNo
Varchar
16
Not Null, required, Renew Data





Media Number


CustomerLabel
Varchar
256
Allows null









Every record in this table will have a unique RecordJobNumber and MediaNumber.
2.2) Table prdFiies
This table contains information on file system files. Each entry in this table has metadata describing either a directory or a file.
The primary key for this table is a forty bytes long field named FileID. This field is computed using the hash algorithm based on values such as the ModifyDate, Type and AsciiName fields. In order to allow configurability to RIFT, the fields used by the hash algorithm will be stored on the registry. Two files that generate the same hash value are considered identical. This field is required and the database will check for its uniqueness.
Fields:













Name
Type
Size
Comments


















FileID
Char
40
Not null, hashed, unique


Type
Varchar
20
Not Null, directory or a file


CreateDate
Datetime
8
Not null


ModifyDate
Datetime
8
Not null


AccessDate
Datetime
8
Not null


Attributes
Varchar
50
Allows null


AsciiName
Varchar
256
Not null


UnicodeName
Nvarchar
256
Allows null


ShortName
Varchar
256
Allows null


ParentID
Char
40
Allows null


HashContent
Char
40
Allows null









Since a directory can contain directories and files, records in this table will have a reference to other records in this table. This reference will be represented by the field ParentID. For the root directory, the ParentID will have a NULL (no value) value. For example, the directory tree below will have the following entries in this table:


















 








ID
ParentID





DIR1
NULL


DIR2
DIR1


DIR3
DIR1


DIR4
DIR2


File1
DIR4


File2
DIR4


File3
DIR3


DIR5
DIR3









The field ContentHash is computed using the hash algorithm on the file's content. For records representing directories, this field will have a NULL value. This field relates this table with the table prdContents.
When a record is deleted from this table, a database trigger will delete related records from the tables prdFileSource and prdFiles (other folders that are children of this record). In addition, this trigger will check and delete records from the prdContents table if the records are not related to other records from the tables prdFiles (file content), prdMailItems (message body) or prdAttachments (attachment content).
2.3) Table prdMailBox
This table contains information on mail boxes from an e-mail system.
The primary key for this table is a forty bytes long field named MailBoxID. This field will be computed base on the RFC 3174 hash algorithm based on the Mail Box metadata. This field is required and the database will check for its uniqueness.
Fields:
















Name
Type
Size
Comments





















MailBoxID
Char
40
Not null, hashed, unique



Name
Char
256
Not null



UserName
Char
256
Allows null



Description
Char
256
Allows null



DisplayName
Char
256
Allows null










The field Name is the unique Mail Box name, such as the “MS Exchange Mail Box Name”.
When a record is deleted from this table, a database trigger will delete related records from the tables prdFileSource and prdMailFolders.
2.4) Table prdFileSource
This table contains data relating records from the prdSource (tapes, file systems, etc) to records from prdMailBoxes, prdMailItems or prdFiles.
RlFT will perform the following steps when a file is being processed:

    
    
        1) RIFT will hash a value based the file metadata.
        2) RIFT will check if there is a record in the prdFiles table whose FileID is the same as the hash value just calculated.
        3) If the record does not exist, a new record will be added to the prdFiles table.
        4) A new record will be added to the prdFileSource table.
        5) RIFT will hash a new value based on the contents of the file.
        6) RIFT will be added a new record to the table prdContents if hash value just calculated does not match one of the records in the prdcontents table.
    
    


For a file system, the prdFileSource table will contain as many records as there are files and directories in the file system. For example, if a tape with a file system has 10 directories and 20 files, the prdFileSource table will contain a total of 30 records. When a backup of this tape is processed by the RIFT system, another 30 records will be added to this table. However, only records for files that are not identical will be added to the tables prdFiles and prdcontents.
For email systems, RlFT will use the same process, storing data in the prdMailBox, prdMailItems, prdAttachments and prdFileSource tables.
The primary key for this table composed by two fields, a forty-bytes long field, FileID and a four-bytes integer field, SourceID. These fields are required and the database will check their uniqueness.
Fields:













Name
Type
Size
Comments


















FileID
Char
40
Not null, required, part of primary key,





originated from tables prdFiles.FileID,





prfMailBoxID or prdMailItems.MailID


SourceID
Int
4
Not null, required, part of primary key,





originated from table prdSource


Type
Varchar
20
Not null


Date
Datetime
8
Not null









The field Type indicates if the FileID field belongs to record from either one of the table prdMailBox, prdMailItem or prdFiles.
The field Date indicates when the record was created, allowing to trace how the filesystem was de-duplicated.
2.5) Table prdMailFolders
This table contains information on mail folders.
The primary key for this table is a forty bytes long field named FolderID. This field will be computed base on the hash algorithm using Mail Folder metadata. This field is required and the database will check for its uniqueness.
Fields:













Name
Type
Size
Comments


















FolderID
Char
40
Not null, hashed, unique


ParentID
Char
40
Not null, originated either





from prdMailBox.MailBoxID





or prdMailFolders.FolderID


Description
Varchar
256
Allows null


FolderType
Int
4
Not null


DisplayName
Varchar
256
Not null


ParentType
Varchar
20
Not null









Since a folder can contain folders and mail items, records in this table will have a reference to other records in this table. This reference will be represented by the field ParentID. For root folder the ParentID field will contain the MailBoxID of the parent Mail Box.
The field MailItemType indicates the folder type (mail, notes, calendar, etc). The field ParentType indicates if the folder parent is a Mail Box or another folder.
Possible values for the FolderType are:
DeletedItems=0x03
Outbox=0x04
SentMail=0x05
Inbox=0x06
Calendar=0x09
Contacts=0x0A
Journal=0x0B
Notes=0x0C
Tasks=0x0D
Drafts=0x10
Other=0x14
When a record is deleted from this table, a database trigger will delete related records from the tables prdMailItems and prdMailFolders (children of this record).
6) Table prdMailItems
This table contains information on mail items: mail messages, tasks, notes, appointments and journals.
The primary key for this table is a forty bytes long field named MailID. This field will be computed base on hash algorithm using the Mail Item metadata. This field is required and the database will check for its uniqueness.
Fields:













Name
Type
Size
Comments


















MailID
Char
40
Not null, hashed, unique


FolderID
Char
40
Not null, relates to





prdMailFolders.FolderID


Subject
Varchar
256
Allows null


From
Varchar
256
Not null


CreateDate
Datetime
8
Not null


SentDate
Datetime
8
Not null


ReceivedDate
Datetime
8
Not null


BodyHash
Char
40
Not null - foreign key on prdContents


Size
Int
4
Allows null


Sensitivity
Int
4
Allows null


Priority
Int
4
Allows null









The CC, To and BCC data are stored in the table prdRecipients.
Possible values for the field Sensitivity are:
Normal=0,
Personal=1,
Private=2,
Confidential=3
Possible values for the field Priority are:
Low=0,
Normal=1,
High=2
The field BodyHash will be computed using the hash algorithm on the file's content. For directories, this field is NULL. This field will relate this table with the table prdContents.
When a record is deleted from this table, a database trigger will delete related records from tables prdAttachments and prdRecipients. In addition, this trigger will check and delete records from the prdcontents table if the records are not related to other records from the tables prdFiles (file content), prdMailItems (message body) or prdAttachments (attachment content).
RIFT will perform the following steps when a file is being processed:

    
    
        1) RlFT will hash a value based the mail item metadata.
    
    


2) RlFT will check if there is a record in the prdMailItems table whose MailID is the same as the hash value just calculated.

    
    
        3) If the record does not exist, a new record will be added to the prdMailItems table.
        4) A new record will be added to the prdFileSource table.
        5) RlFT will hash a new value based on the contents of the email body.
        6) RlFT will be added a new record to the table prdcontents if hash value just calculated does not match one of the records in the prdcontents table.
        7) Add records for recipients (To, CC and BCC)
    
    


2.7) TableprdRecipients
This table contains information on mail items recipients: To, CC, BCC.
The primary key for this table is a combination of the fields MailID, Type and eMail. These fields are required and the will make the record unique.
Fields:













Name
Type
Size
Comments


















MailID
Char
40
Not null, relates to prdMailItems.MailID


Type
Char
3
Not null, possible values: BCC, CC or To


Email
Varchar
256
Allows null, Recipient's e-mail address









2.8) Table prdAttachments
This table contains information on attachments.
The primary key for this table is a forty bytes long field named AttachmentID. This field will be computed base on the hash algorithm using the attachment display name and file name. This field is required and the database will check for its uniqueness.
Fields:













Name
Type
Size
Comments


















AttachID
Char
40
Not null, hashed, unique


Mailed
Char
40
Not null, relates to





prdMailItems.MailID


DisplayName
Varchar
256
Not null


FileName
Varchar
256
Allows null


ContentHash
Char
40
Not null, relates record to record on





prdContents









The field ContentHash is computed using the hash algorithm using the attachment's file content, This field will relate this table with the table prdContents.
A database trigger will check and delete records from the prdContents table if the records are not related to other records from the tables prdFiles (file content), prdMailItems (message body) or prdAttachments (attachment content).
2.9) Table prdContents
This table contains contents of files, mail item bodies and attachments.
The primary key for this table is a forty bytes long field named HashContent. This field will be computed base on the hash algorithm on the content. This field is required and the database will check it for uniqueness.
Fields:













Name
Type
Size
Comments







ContentHash
Char
40
Not null, relates to prdFiles.ContentHash





or prdMailItem.BodyHash or





prdAttachments.ContentHash


Contents
Image
16
Not null









Examples 2-5
To illustrate the following examples, in FIGS. 7-10 there are two pieces of source media, tape AA and tape BA. On tape A there is one file, called file 1A, on tape BA there is one file, called file 2A. For each file, there is associated content, called respectively content 1A and content 2A.
Example 2
Illustrated in FIG. 7. The metadata and content of files 1A and 2A do not match. The resulting structure in the database may include two separate file entries with links back to the source media and links to their respective content.
Example 3
Illustrated in FIG. 8. The metadata of file 1A and file 2A do not match, but content 1A matches content 2A. The resulting structure in the database would be two separate file entries with links back to the source media, and the links from file 1A and file 2A to their content both point to the same content value. This is an example of content de-duplication.
Example 4
Illustrated in FIG. 9. If the exact same file appears on two different pieces of source media, this may be an example of full file de-duplication. In this case, both file 1A and file 2A may have identical metadata and identical content. The resulting database structure may be to have a single file record with links back to each source media that the file appeared on, and a link to the content.
Example 5
Illustrated FIG. 10. In the unlikely event of two files having identical metadata but different content, the file record may only be present once, with the two files being distinguished by a de-duplication history table (which tells which piece of content belongs to which file at what instance in time).
In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims.

## Claims

1. A method utilizing one or more computer systems for creating a data set without duplication, from data taken from one or more database sources, comprising the steps of:
in a first phase, using the one or more computer systems to traverse files contained in one or more custodian containers of the database sources and creating indices of the custodian containers, the indices comprising (i) hash keys representing the data files and (ii) seek information for locating and handling the data files;
in a second phase, creating at the database sources, a master key table of unique hash keys and seek information from all the data indices created; and
in a third phase, using the one or more computer systems to query the master key table of unique hash keys and using the seek information to produce the data files associated with the hash keys to a storage system,
wherein there are at least two custodian containers, and a first phase on a second container is configured to perform substantially in parallel with a second phase on a first container upon completion of a first phase on the first container.

2. A system for creating a data set without duplication, from data taken from one or more database sources associated with the system, comprising:
(a) one or more computer systems configured to traverse one or more files contained in one or more custodian containers of the database sources and configured to create indices of the custodian containers, the indices comprising (i) hash keys representing the data files and (ii) seek information for locating and handling the data files;
(b) a module at the database sources configured to create a master key table of unique hash keys and seek information from all the data indices created; and
(c) a query capability associated with the one or more computer systems configured to query the master key table of unique hash keys and configured to use the seek information to produce the data files associated with the hash keys;
a storage system for accepting the data files that are produced,
wherein there are at least two custodian containers, and the system is configured to commence a first operation described in (a) on a second container substantially in parallel with a second operation described in (b) on a first container upon completion of a first operation on the first container.

3. A method as defined in claim 1, wherein the method is performed globally on more than one custodian container.

4. A method as defined in claim 1, wherein the method is performed on each custodian container and a data set is created for each custodian container.

5. A system as defined in claim 2, wherein the system performs operations globally on more than one custodian container.

6. A system as defined in claim 2, wherein the system performs operations on each custodian container and creates a data set for each custodian container.