PARTIAL FILE RESTORE IN A DATA STORAGE SYSTEM

• US 20140201155A1
• 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 9,811,423 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 storing files in secondary storage in a data storage system, comprising:

initiating copying of a plurality of files from primary storage to secondary storage, wherein data stored on the secondary storage is organized in one or more chunks, each chunk being a logical data unit;

copying a first portion of a first file of the plurality of files from the primary storage to a buffer for writing to the secondary storage;

creating a first entry in an index associated with a first chunk of the one or more chunks, the index stored in association with the first chunk, the first entry corresponding to the first portion of the first file and comprising;

a first application offset corresponding to the first portion and associated with a software application used to access the first file; and

a first secondary storage offset indicating a location of the first portion within the first chunk in the secondary storage;

copying a second portion of the first file from the primary storage to the buffer for writing to the secondary storage;

creating a second entry in the index associated with the first chunk, the second entry comprising;

a second application offset corresponding to the second portion and associated with the software application; and

a second secondary storage offset indicating a location of the second portion within the first chunk in the secondary storage;

writing the first portion to the location indicated by the first secondary storage offset; and

writing the second portion to the location indicated by the second secondary storage offset.

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

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

4. The method of claim 1, wherein the first application offset indicates a start of the first portion of the first file and the second application offset indicates a start of the second portion of the first file.

5. The method of claim 1, wherein the first entry is written to the secondary storage substantially concurrently with the writing of the first portion of the first file to the first chunk, and the second entry is written to the secondary storage substantially concurrently with the writing of the second portion of the first file to the first chunk.

6. The method of claim 1, further comprising:

copying a third portion of the first file from the primary storage to the buffer for writing to the secondary storage; and

creating a third entry in the index associated with the first chunk, the third entry comprising;

a third application offset corresponding to the third portion of the first file and associated with the software application; and

a third secondary storage offset indicating a location of the third portion within the first chunk in the secondary storage,

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 7, wherein said writing the first portion to the location indicated by the first secondary storage offset comprises deduplicating or compressing the first portion.

9. The method of claim 1, wherein the first chunk comprises metadata information relating to the first file stored in association with the first file.

10. The method of claim 1, further comprising:

copying a third portion of the first file from the primary storage to the buffer for writing to the secondary storage;

creating a third entry in a second index associated with a second chunk of the one or more chunks, the second index stored in association with the second chunk, the third entry corresponding to the third portion of the first file and comprising;

a third application offset corresponding to the third portion and associated with the software application;

a third secondary storage offset indicating a location of the third portion within the second chunk in the secondary storage; and

corresponding byte position information relating to a byte position of the third portion within the second chunk; and

writing the third portion to the location indicated by the third second storage offset.

11. A data storage system for storing files in secondary storage, comprising:

a storage manager executing on computer hardware and configured to;

initiate copying of a plurality of files from primary storage to secondary storage, wherein data stored on the secondary storage is organized in one or more chunks, each chunk being a logical data unit; and

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

copy a first portion of the first file of the plurality of files from the primary storage to a buffer for writing to the secondary storage;

create a first entry in an index associated with a first chunk of the one or more chunks, the index stored in association with the first chunk, the first entry corresponding to the first portion of the first file and comprising;

a first application offset corresponding to the first portion and associated with a software application used to access the file; and

a first secondary storage offset indicating a location of the first portion within the first chunk in the secondary storage;

copy a second portion of the first file from the primary storage to the buffer for writing to the secondary storage;

create a second entry in the index associated with the first chunk, the second entry comprising;

a second application offset corresponding to the second portion and associated with the software application; and

a second secondary storage offset indicating a location of the second portion within the first chunk in the secondary storage;

write the first portion to the location indicated by the first secondary storage offset; and

write the second portion to the location indicated by the second secondary storage offset.

12. The system of claim 11, wherein the index is contained within the first chunk.

13. The system of claim 11, wherein each of the one or more chunks is of equal size.

14. The system of claim 11, wherein the first application offset indicates a start of the first portion of the first file and the second application offset indicates a start of the second portion of the first file.

15. The system of claim 11, wherein the first entry is written to the secondary storage substantially concurrently with the writing of the first portion of the first file to the first chunk, and the second entry is written to the secondary storage substantially concurrently with the writing of the second portion of the first file to the first chunk.

16. The system of claim 11, wherein the one or more computing devices are further configured to:

copy a third portion of the first file from the primary storage to the buffer for writing to the secondary storage; and

create a third entry in the index associated with the first chunk, the third entry comprising;

a third application offset corresponding to the third portion and associated with the software application; and

a third secondary storage offset indicating a location of the third portion within the first chunk in the secondary storage,

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.

17. The system of claim 16, wherein a third interval between the first secondary storage offset and the second secondary storage offset of the secondary copy is different from a fourth interval between the second secondary storage offset and the third secondary storage offset.

18. The system of claim 11, wherein the writing of the first portion to the location indicated by the first secondary storage offset is performed at least in part by deduplicating or compressing the first portion.

19. The system of claim 11, wherein the first chunk comprises metadata information relating to the first file stored in association with the first file.

20. The system of claim 11, wherein the one or more computing devices are further configured to:

copy a third portion of the first file from the primary storage to the buffer for writing to the secondary storage;

create a third entry in a second index associated with a second chunk of the one or more chunks, the second index stored in association with the second chunk, the third entry corresponding to the third portion of the first file and comprising;

a third application offset corresponding to the third portion and associated with the software application;

a third secondary storage offset indicating a location of the third portion in the secondary storage; and

corresponding byte position information relating to a byte position of the third portion within the second chunk; and

write the third portion to the location indicated by the third secondary storage offset within the second chunk.