System and method for storing redundant information

• US 8,285,683 B2
• Filed: 09/30/2011
• Issued: 10/09/2012
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: CommVault Systems Incorporated
• Original Assignee: CommVault Systems Incorporated
• Inventors: Prahlad, Anand, Gokhale, Parag, Kottomtharayil, Rajiv, Retnamma, Manoj K. Vijayan, Attarde, Deepak R.
• Primary Examiner(s): Beausoliel, Jr., Robert
• Assistant Examiner(s): ALLEN, NICHOLAS E
• Application Number:
  US13/251,022
• Publication Number:
  US 20120023070A1
• Time in Patent Office: 375 Days
• Field of Search: 707/652
• US Class Current: 707/652
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 16/1748 De-duplication implemented within the file system, e.g. based on file segments de-duplication techniques in storage systems for the management of data blocks G06F3/0641
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0638 Organizing or formatting or addressing of data
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G11B 5/86 Re-recording, i.e. transcribing information from one magnetisable record carrier on to one or more similar or dissimilar record carriers by varying the order of the information G11B27/029, G11B27/036

Abstract

A method and system for reducing storage requirements and speeding up storage operations by reducing the storage of redundant data includes receiving a request that identifies one or more data objects to which to apply a storage operation. For each data object, the storage system determines if the data object contains data that matches another data object to which the storage operation was previously applied. If the data objects do not match, then the storage system performs the storage operation in a usual manner. However, if the data objects do match, then the storage system may avoid performing the storage operation.

Claims

1. A method in a computer system for restoring data from a deduplicated copy, the method comprising:

receiving a request to restore to a destination location one or more data objects originally located within a hierarchy,

wherein the copy of data contains information describing the hierarchy, but only contains a reduced instance of each data object of the hierarchy for storage on sequential media, and

wherein the request specifies an original location within the hierarchy of the data objects to be restored;

for each data object in the request;

determining whether the data at the original location within the hierarchy specified by the request contains the data object itself or a reference to a data object and the data object is stored elsewhere;

wherein the request contains a digest value for identifying each data object,

wherein the determining comprises comparing the digest value to an index of digest values of data objects stored within the computer system;

if the original location within the hierarchy specified by the request contains a reference to a data object, resolving the reference to find the data object and copying the data object to the destination location; and

if the original location within the hierarchy specified by the request contains the data object itself, copying the data object to the destination location.

2. The method of claim 1 wherein the hierarchy is a file system hierarchy, and wherein the copy of data contains a reduced instance of the data of each file in the file system hierarchy, and wherein additional instances of each file in the original location are stored as stubs within the copy of data that reference the single instance of the data of each file.

3. The method of claim 1 wherein the reference further comprises a pointer to the location of the actual data for the data object, and wherein resolving the reference comprises locating the actual data based on the pointer.

4. The method of claim 1 wherein the one or more data objects are email messages and wherein the hierarchy comprises folders within an email message store.

5. The method of claim 1 wherein the copy of data is stored on one or more sequential media, wherein the reference further comprises a media identifier and offset of the actual data object, and wherein resolving the reference comprises locating the media identified by the media identifier and seeking to the offset.

6. The method of claim 1 wherein the copying the data object to the destination location further comprises decrypting the data object.

7. A system for improving the retrieval of a data object in a network environment that contains multiple instances of the data object, the system comprising:

at least one processor;

at least one memory, coupled to the processor;

means, coupled among the at least one processor and memory, for receiving a request to access the data object at a first location;

means, coupled among the at least one processor and memory, for determining at least one alternative location of an instance of the requested data object, wherein the at least one alternative location is not the first location;

means, coupled among the at least one processor and memory, for selecting an instance of the data object from among the determined at least one alternative location to use to satisfy the request; and

means, coupled among the at least one processor and memory, for sending the selected instance of the data object in response to the request,

wherein, coupled among the at least one processor and memory, the request contains a digest value for identifying the data object, and

wherein, coupled among the at least one processor and memory, determining the at least one alternative location of an instance of the requested data object comprises comparing the digest value to an index of digest values of data objects stored within the network environment.

8. The system of claim 7 wherein a computer system from which the request is received is closer to the selected alternative location than to the first location.

9. The system of claim 7 wherein the request is an HTTP request for a data object located on the world wide web, and wherein the alternative location is a location within a private local area network.

10. The system of claim 7 wherein the means for selecting an instance of the data object comprises means for determining the fastest location from which the data object is available.

11. The system of claim 7 wherein the means for selecting an instance of the data object comprises means for identifying multiple copies containing instances of the data object and determining attributes of each copy that affect an accessing speed for the data object.

12. The system of claim 7 wherein the means for sending the selected instance of the data object comprises means for copying the data object from the selected alternative location to an intermediate location, and then from the intermediate location to a location specified in the request.

13. At least one tangible computer-readable medium storing instructions, which when executed by at least one data processing device performs a method for restoring data from a deduplicated copy, comprising:

receiving a request to restore to a destination location one or more data objects originally located within a hierarchy,

wherein the copy of data contains information describing the hierarchy, but only contains a reduced instance of each data object of the hierarchy for storage on sequential media, and

wherein the request specifies an original location within the hierarchy of the data objects to be restored;

for each data object in the request;

determining whether the data at the original location within the hierarchy specified by the request contains the data object itself or a reference to a data object and the data object is stored elsewhere;

wherein the request contains a digest value for identifying each data object,

wherein the determining comprises comparing the digest value to an index of digest values of data objects stored within a computer system;

if the original location within the hierarchy specified by the request contains a reference to a data object, resolving the reference to find the data object and copying the data object to the destination location; and

if the original location within the hierarchy specified by the request contains the data object itself, copying the data object to the destination location.

14. The tangible computer-readable medium of claim 13 wherein the hierarchy is a file system hierarchy, and wherein the copy of data contains a reduced instance of the data of each file in the file system hierarchy, and wherein additional instances of each file in the original location are stored as stubs within the copy of data that reference the single instance of the data of each file.

15. The tangible computer-readable medium of claim 13 wherein the reference further comprises a pointer to the location of the actual data for the data object, and wherein resolving the reference comprises locating the actual data based on the pointer.

16. The tangible computer-readable medium of claim 13 wherein the one or more data objects are email messages and wherein the hierarchy comprises folders within an email message store.

17. The tangible computer-readable medium of claim 13 wherein the copy of data is stored on one or more sequential media, wherein the reference further comprises a media identifier and offset of the actual data object, and wherein resolving the reference comprises locating the media identified by the media identifier and seeking to the offset.

18. The tangible computer-readable medium of claim 13 wherein the copying the data object to the destination location further comprises decrypting the data object.