PARTIAL FILE RESTORE IN A DATA STORAGE SYSTEM

• US 20140201153A1
• Filed: 01/10/2014
• Published: 07/17/2014
• Est. Priority Date: 01/11/2013
• Status: Active Grant

• Current Assignee: CommVault Systems Incorporated
• Original Assignee: CommVault Systems Incorporated
• Inventors: Vijayan, Manoj Kumar, Attarde, Deepak Raghunath
• Granted Patent: US 9,804,930 B2
• Time in Patent Office: Days
• US Class Current: 707/647
• CPC Class Codes: G06F 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

The data storage system according to certain aspects can implement partial file restore, where only a portion of the secondary copy of a file is restored. Such portion may be designated by one or more application offsets for the file. The system may provide an in-chunk index that includes mapping information between the application offsets and the secondary copy offsets. Chunks may refer to logical data units in which secondary copies are stored, and the in-chunk index for a chunk may be stored in secondary storage with the chunk. Because the mapping information may not be provided at a fixed interval, the system can search through application offsets in the in-chunk index to locate the secondary copy offset corresponding to the portion application offset(s). In this manner, the system may restore the designated portion of the secondary copy in a fast and efficient manner by using the in-chunk index.

Claims

1. A method of partially restoring a secondary copy of a file stored in a data storage system, comprising:

receiving an instruction to restore a portion of a secondary copy of a file stored in secondary storage to primary storage for use by a software application, data stored in the secondary storage being organized in one or more chunks, each chunk being a logical data unit,

wherein the instruction comprises a starting application offset corresponding to a beginning of the portion of the file to be restored, the starting application offset associated with the software application;

identifying, using computer hardware, a chunk in the secondary storage that includes a part of the secondary copy corresponding to the starting application offset;

accessing, using computer hardware, an index stored in association with the chunk, wherein the index comprises a plurality of entries, each entry of the plurality of entries listing and providing a mapping between a respective application offset and a corresponding respective secondary storage offset, the respective application offset associated with the software application, the respective secondary storage offset corresponding to an offset within the secondary copy of the file;

determining, using computer hardware, a first entry in the plurality of entries that references a respective application offset that corresponds to the starting application offset; and

using the respective secondary storage offset of the first entry to restore a portion in the chunk from the secondary storage to the primary storage.

2. The method of claim 1, wherein the first entry is an entry of the plurality of entries that references a respective application offset that is the same as the starting application offset or is closer in value to the starting application offset than any of other entries in the plurality of entries.

3. The method of claim 1, further comprising, in response to determining an entry in the plurality of entries that references a respective application offset that is the closest to the starting application offset, sending the application offset that is the closest to the starting application offset to the software application.

4. The method of claim 1, wherein the index is contained within the chunk.

5. The method of claim 1, wherein each of the one or more chunks is of equal size.

6. The method of claim 1, wherein the plurality of entries comprises:

a first entry comprising a first application offset and a first secondary storage offset that corresponds to the first application offset;

a second entry comprising a second application offset and a second secondary storage offset that corresponds to the second application offset; and

a third entry comprising a third application offset and a third secondary storage offset that corresponds to the third application offset,

wherein a first interval between the first application offset and the second application offset is different from a second interval between the second application offset and the third application offset.

7. The method of claim 6, wherein a third interval between the first secondary storage offset and the second secondary storage offset is different from a fourth interval between the second secondary storage offset and the third secondary storage offset.

8. The method of claim 1, wherein the instruction comprises an end application offset indicating an end of the portion of the file to be restored.

9. The method of claim 1, wherein a size of the portion in the chunk that is restored to the primary storage is a predetermined number of bytes from the secondary storage offset in the first entry.

10. The method of claim 1, wherein the starting application offset is selected in a graphical user interface of the software application.

11. The method of claim 1, wherein the secondary copy comprises metadata information relating to the secondary copy.

12. The method of claim 1, wherein each entry in the plurality of entries comprises physical byte position information that indicates a byte position in the chunk that corresponds to the application offset in the entry.

13. The method of claim 12, wherein said using the respective secondary storage offset of the first entry to restore a portion in the chunk comprises restoring a portion of the chunk that begins with a start position that is indicated by the physical byte position information.

14. The method of claim 1, wherein said determining a first entry in the plurality of entries comprises performing a binary search on the plurality of entries.

15. The method of claim 1, wherein the secondary copy of the file is deduplicated or compressed.

16. A data storage system for partially restoring a secondary copy of a file, comprising:

a storage manager executing on computer hardware and configured to;

receive an instruction to restore a portion of a secondary copy of a file stored in secondary storage to primary storage for use by a software application, data stored in the secondary storage being organized in one or more chunks, each chunk being a logical data unit,

wherein the instruction comprises a starting application offset corresponding to a beginning of the portion of the file to be restored, the starting application offset associated with the software application; and

one or more computing devices comprising computer hardware and configured to;

identify a chunk in the secondary storage that includes a part of the secondary copy corresponding to the starting application offset;

access an index stored in association with the chunk, wherein the index comprises a plurality of entries, each entry of the plurality of entries listing and providing a mapping between a respective application offset and a corresponding respective secondary storage offset, the respective application offset associated with the software application, the respective secondary storage offset corresponding to an offset within the secondary copy of the file;

determine a first entry in the plurality of entries that references a respective application offset that corresponds to the starting application offset; and

use the respective secondary storage offset of the first entry to restore a portion in the chunk from the secondary storage to the primary storage.

17. The system of claim 16, wherein the first entry is an entry of the plurality of entries that references a respective application offset that is the same as the starting application offset or is closer in value to the starting application offset than any of other entries in the plurality of entries.

18. The system of claim 16, wherein the plurality of entries comprises:

a first entry comprising a first application offset and a first secondary storage offset that corresponds to the first application offset;

a second entry comprising a second application offset and a second secondary storage offset that corresponds to the second application offset; and

a third entry comprising a third application offset and a third secondary storage offset that corresponds to the third application offset,

wherein a first interval between the first application offset and the second application offset is different from a second interval between the second application offset and the third application offset.

19. The system of claim 16, wherein each entry in the plurality of entries comprises physical byte position information that indicates a byte position in the chunk that corresponds to the application offset in the entry.

20. The system of claim 16, wherein the one or more computing devices perform the determination of a first entry in the plurality of entries at least in part by performing a binary search on the plurality of entries.