Generating data set views for backup restoration

• US 8,756,197 B1
• Filed: 08/13/2010
• Issued: 06/17/2014
• Est. Priority Date: 08/13/2010
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Wilde, Robert, Schiefelbein, Larry
• Primary Examiner(s): Woo, Issac M
• Application Number:
  US12/856,557
• Time in Patent Office: 1,404 Days
• Field of Search: 707600-899
• US Class Current: 707/640
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 16/00 Information retrieval; Database structures therefor; File system structures therefor
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A system and method for creating a consistent view of previously backed up data. In one embodiment, a point in time copy of a set of data is requested. The point in time copy includes a base image of the set of data and additional data corresponding to transactions targeted to the set of data which are received during creation of the point in time copy. A subset of the additional data usable to generate a consistent view of the set of data from the base image is determined. A file that includes a set of changes to the base image represented by the subset is created and stored in association with the base image. Responsive to a request for access to the copy, the previously stored subset is utilized to create a consistent virtual view of the copy from the base image.

Claims

1. A method for use in a computing system, the method comprising:

receiving a request to create a point in time copy of a set of data, wherein the point in time copy comprises a base image of the set of data and additional data corresponding to transactions targeted to the set of data which are received during creation of the point in time copy, wherein the transactions are not yet applied to the base image;

determining a subset of the additional data usable to generate a consistent view of the set of data from the base image;

creating a file that comprises a set of changes to the base image represented by the subset; and

storing the file in association with the base image.

2. The method of claim 1, further comprising:

receiving a request to access a backup of the set of data;

responsive to the request, generating the consistent view of the set of data by applying a set of changes to the base image represented by the file to a backup of the base image; and

simulating access to the backup of the set of data by providing access to the consistent view of the set of data.

3. The method of claim 1, wherein determining the subset comprises:

reading a checkpoint file; and

determining from content of the checkpoint file whether a transaction represented by a selected item of the additional data has been written to the set of data.

4. The method of claim 1, wherein the simulating access to the backup of the set of data further comprises delivering a database entry from a database represented by the set of data.

5. The method of claim 1, wherein creating the file further comprises blocking a write, recording the write, and recording the location to which the write was directed.

6. The method of claim 1, wherein applying the set of changes to the base image represented by the file to the backup of the base image further comprises determining the relevant writes of the file by examining a list representing the subset.

7. The method of claim 1, wherein a time of the consistent view can be altered by applying from a second file to the backup of the base image a second set of changes representing a second subset of the additional data.

8. The method of claim 1, further comprising confirming that the transactions corresponding to the subset of the additional data have been performed by reading the file.

9. A non-transitory computer readable storage medium comprising program instructions, wherein when executed the program instructions are operable to:

receiving a request to create a point in time copy of a set of data, wherein the point in time copy comprises a base image of the set of data and additional data corresponding to transactions targeted to the set of data which are received during creation of the point in time copy, wherein the transactions are not yet applied to the base image;

determine a subset of the additional data usable to generate a consistent view of the set of data from the base image;

create a file that comprises a set of changes to the base image represented by the subset; and

store the file in association with the base image.

10. The computer readable storage medium of claim 9, wherein when executed the program instructions are further operable to:

receive a request to access a backup of the set of data;

responsive to the request, generate the consistent view of the set of data by applying a set of changes to the base image represented by the file to a backup of the base image; and

simulate access to the backup of the set of data by providing access to the consistent view of the set of data.

11. The computer readable storage medium of claim 9, wherein the instructions operable to determine the subset further comprise instructions operable to:

read a checkpoint file, and

determine from content of the checkpoint file whether a transaction represented by a selected item of the additional data has been written to the set of data.

12. The computer readable storage medium of claim 9, wherein the instructions operable to simulate the access to the backup of the set of data further comprise instructions operable to deliver a database entry from a database represented by the set of data.

13. The computer readable storage medium of claim 9, wherein the instructions operable to create the file further comprise instructions operable to block a write, record the write, and record the location to which the write was directed.

14. The computer readable storage medium of claim 9, wherein the instructions operable to apply the set of changes to the base image represented by the file to the backup of the base image further comprise instructions operable to determine the relevant writes of the file by examining a list representing the subset.

15. The computer readable storage medium of claim 9, wherein a time of the consistent view can be altered by applying from a second file to the backup of the base image a second set of changes representing a second subset of the additional data.

16. A system comprising:

a backup application configured to;

receive a request to create a point in time copy of a set of data, wherein the point in time copy comprises a base image of the set of data and additional data corresponding to transactions targeted to the set of data which are received during creation of the point in time copy, wherein the transactions are not yet applied to the base image;

determine a subset of the additional data usable to generate a consistent view of the set of data from the base image; and

create a file that comprises a set of changes to the base image represented by the subset;

a storage server configured to store the file in association with the base image.

17. The system of claim 16, wherein the backup application is further configured to:

receive a request to access a backup of the set of data;

responsive to the request, generate the consistent view of the set of data by applying a set of changes to the base image represented by the file to a backup of the base image; and

simulate access to the backup of the set of data by providing access to the consistent view of the set of data.

18. The system of claim 16, wherein the backup application is further configured to:

read a checkpoint file; and

determine from content of the checkpoint file whether a transaction represented by a selected item of the additional data has been written to the set of data.

19. The system of claim 16, wherein the backup application is further configurable to deliver a database entry from a database represented by the set of data.

20. The system of claim 16, wherein the backup application is further configurable to block a write, record the write, and record the location to which the write was directed.