Restoration of backed up data by restoring incremental backup(s) in reverse chronological order

• US 7,802,134 B1
• Filed: 08/18/2005
• Issued: 09/21/2010
• Est. Priority Date: 08/18/2005
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Sobel, William E., McCorkendale, Bruce
• Primary Examiner(s): Baderman; Scott T
• Assistant Examiner(s): PATEL, KAMINI B
• Application Number:
  US11/206,896
• Time in Patent Office: 1,860 Days
• Field of Search: 714/15
• US Class Current: 714/15
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1469 Backup restoration techniques

Abstract

Restoring of content of data blocks to non-volatile storage as the content existed at a particular instant in time. After accessing the last backup representing the most recent backup of the plurality of data blocks prior to the particular instant in time, the content of each data block represented in the last backup is written to a corresponding position in the non-volatile storage. This last backup may be an incremental backup in which only those data blocks that had changed since the immediate prior backup were actually backed up. Then, restoration occurs through each prior backup in reverse chronologic order until the full backup is encountered and restored. When restoring a backup, a data block is not restored if the data block had already been restored proceeding in reverse chronological order.

Claims

1. A method for restoring content of a plurality of data blocks to non-volatile storage as the content existed at a particular instant in time, the method comprising:

an act of accessing a last backup representing the most recent backup of the plurality of data blocks prior to the particular instant in time;

an act of writing the content of each data block represented in the last backup to a corresponding position in the non-volatile storage;

an act of accessing a second-to-last backup representing the second most recent backup of at least a portion of the plurality of data blocks prior to the particular instant in time; and

after the act of writing the content of each data block represented in the last backup, an act of performing a non-overlapping write of the second-to-last backup by performing the following;

for each of at least one data block that is represented in the second-to-last backup, but is not represented in the last backup, an act of writing the data block of the second-to-last backup to the non-volatile storage; and

for each of at least one data block that is represented in the second-to-last backup, and is also represented in the last backup, an act of refraining from writing the data block of the second-to-last backup.

2. A method in accordance with claim 1, wherein the last backup is an incremental backup, and the second to last backup is also an incremental backup of the plurality of data blocks.

3. A method in accordance with claim 1, wherein the last backup is an incremental backup, and the second-to-last backup is a full backup of the plurality of data blocks.

4. A method in accordance with claim 1, further comprising the following:

an act of accessing a third-to-last backup representing the third most recent backup of at least a portion of the plurality of data blocks prior to the particular instance in time; and

after the act of performing a non-overlapping write of the second-to-last backup, an act of performing a non-overlapping write of the third-to-last backup by performing the following;

for each of at least one data block that is represented in the third-to-last backup, but is not represented in either the second-to-last or the last backup, an act of writing the data block of the third-to-last backup to the non-volatile storage; and

for each of at least one data block that is represented in the third-to-last backup, and is also represented in either or both of the second-to-last or the last backup, an act of refraining from writing the data block of the third-to-last backup.

5. A method in accordance with claim 4, wherein the last, second-to-last, and third-to-last backups are each incremental backups of the plurality of data blocks.

6. A method in accordance with claim 4, wherein the last and second-to-last backups are each incremental backups of the plurality of data blocks, and the third-to-last backup is a full backup of the plurality of data blocks.

7. A method in accordance with claim 6, further comprising:

an act of repeating the act of performing a non-overlapping write in reverse chronological order until the act of performing is performed for a full backup for the plurality of data blocks.

8. A method in accordance with claim 1, wherein the plurality of data blocks are each sectors, and the non-volatile storage is a disk drive.

9. A method in accordance with claim 1, further comprising:

an act of tracking which data blocks have been restored already as part of the restoration;

an act of identifying the at least one data block that is represented in the second-to-last backup, but is not represented in the last backup, using results of the act of tracking; and

an act of identifying the at least one data block that is represented in the second-to-last backup, and is also represented in the last backup, using the results of the act of tracking.

10. A method in accordance with claim 9, wherein the act of tracking is performed using a bitmap with one bit for each of the plurality of data blocks representing whether or not the data block has already been restored as part of the restoration.

11. A method in accordance with claim 9, wherein the act of tracking is performed using a bitmap with one bit for each of one or more subranges of the plurality of data blocks.

12. A computer program product comprising one or more computer-readable storage media having thereon computer-executable instructions that, when executed by one or more processors of a computing system, cause the computing system to perform a method for restoring content of a plurality of data blocks to non-volatile storage as the content existed at a particular instant in time, the method comprising:

an act of accessing a last backup representing the most recent backup of the plurality of data blocks prior to the particular instant in time;

an act of writing the content of each data block represented in the last backup to a corresponding position in the non-volatile storage;

an act of accessing a second-to-last backup representing the second most recent backup of at least a portion of the plurality of data blocks prior to the particular instance in time; and

after the act of writing the content of each data block represented in the last backup, an act of performing a non-overlapping write of the second-to-last backup by performing the following;

for each of at least one data block that is represented in the second-to-last backup, but is not represented in the last backup, an act of writing the data block of the second-to-last backup to the non-volatile storage; and

for each of at least one data block that is represented in the second-to-last backup, and is also represented in the last backup, an act of refraining from writing the data block of the second-to-last backup.

13. A computer program product in accordance with claim 12, wherein the one or more computer-readable media are system memory.

14. A computer program product in accordance with claim 12, wherein the one or more computer-readable media are non-volatile storage.

15. A method for restoring content of a plurality of data blocks to non-volatile storage as the content existed at a particular instant in time, the method comprising:

an act of accessing a last backup representing the most recent backup of the plurality of data blocks prior to the particular instant in time, wherein the last backup is an incremental backup;

an act of writing the content of each data block represented in the last backup to a corresponding position in the non-volatile storage; and

a step for non-redundantly restoring each preceding backup in reverse chronological order until a full backup corresponding to the incremental backup is restored.

16. A method in accordance with claim 15, wherein the step for non-redundantly restoring each preceding backup in reverse chronological order comprises:

an act of accessing a second-to-last backup representing the second most recent backup of at least a portion of the plurality of data blocks prior to the particular instant in time; and

after the act of writing the content of each data block represented in the last backup, an act of performing a non-overlapping write of the second-to-last backup by performing the following;

for each of at least one data block that is represented in the second-to-last backup, but is not represented in the last backup, an act of writing the data block of the second-to-last backup to the non-volatile storage; and

for each of at least one data block that is represented in the second-to-last backup, and is also represented in the last backup, an act of refraining from writing the data block of the second-to-last backup.

17. A computing system comprising the following:

a non-volatile storage comprising a plurality of data blocks;

one or more processors;

a restoration mechanism configured to perform a recovery method comprising;

an act of accessing a last backup representing the most recent backup of the plurality of data blocks prior to a particular instant in time;

an act of writing the content of each data block represented in the last backup to a corresponding position in the non-volatile storage;

an act of accessing a second-to-last backup representing the second most recent backup of at least a portion of the plurality of data blocks prior to the particular instant in time; and

after the act of writing the content of each data block represented in the last backup, an act of performing a non-overlapping write of the second-to-last backup by performing the following;

for each of at least one data block that is represented in the second-to-last backup, but is not represented in the last backup, an act of writing the data block of the second-to-last backup to the non-volatile storage; and

for each of at least one data block that is represented in the second-to-last backup, and is also represented in the last backup, an act of refraining from writing the data block of the second-to-last backup.

18. A computing system in accordance with claim 17, further comprising:

a memory having thereon computer-executable instructions that are structured such that when executed by the one or more processors, the recovery mechanism is caused to perform the recovery method.

19. A computing system in accordance with claim 18, wherein the memory is volatile system memory.

20. A computing system in accordance with claim 18, wherein the memory is non-volatile storage.

21. A method for backing up a plurality of data blocks, comprising:

creating a first backup of at least a portion of the plurality of data blocks, the first backup comprising a copy of at least a portion of the plurality of data blocks;

after creating the first backup, creating a second backup of at least a portion of the plurality of data blocks, the second backup comprising a copy of at least a portion of the plurality of data blocks;

identifying, by comparing the second backup with the first backup, one or more data blocks within the second backup that have been modified since creation of the first backup;

creating a file that identifies each data block within the second backup that has been modified since creation of the first backup, wherein the file identifies data blocks within the second backup that are to be restored in place of corresponding data blocks within the first backup during a reverse-chronological restore operation; and

storing the file.

22. The method of claim 21, wherein the file comprises a bitmap that comprises at least one bit for each data block within the second backup that has been modified since creation of the first backup.

23. The method of claim 22, wherein the bitmap further comprises at least one bit for each of one or more subranges of the plurality of data blocks.

24. The method of claim 21, wherein the first backup is a full backup and the second backup is an incremental backup.

25. The method of claim 21, wherein the first backup is an incremental backup.

26. The method of claim 21, wherein the file enables restoring the second backup prior to restoring the first backup without performing substantial duplicative write operations.

27. A method for backing up a plurality of data blocks, comprising:

creating a first backup of at least a portion of the plurality of data blocks, the first backup comprising a copy of at least a portion of the plurality of data blocks;

after creating the first backup, creating a second backup of at least a portion of the plurality of data blocks, the second backup comprising a copy of at least a portion of the plurality of data blocks;

identifying, by comparing the second backup with the first backup, one or more data blocks within the second backup to be restored in place of corresponding data blocks within the first backup during a reverse-chronological restore operation;

creating a file that identifies each data block within the second backup that is to be restored in place of corresponding data blocks within the first backup during the reverse-chronological restore operation; and

storing the file.

28. The method of claim 27, wherein the reverse-chronological restore operation comprises a restore operation in which the second backup is restored prior to restoring the first backup.

29. The method of claim 27, wherein the file further identifies each data block within the second backup that has been modified since creation of the first backup.

30. The method of claim 27, wherein the file comprises a bitmap that comprises at least one bit for each data block within the second backup that is to be restored in place of corresponding data blocks within the first backup during the reverse-chronological restore operation.

31. The method of claim 27, wherein the file comprises a bitmap that comprises at least one bit for each data block within the second backup that has been modified since creation of the first backup.

32. The method of claim 31, wherein the bitmap further comprises at least one bit for each of one or more subranges of the plurality of data blocks.

33. The method of claim 27, wherein the first backup is a full backup and the second backup is an incremental backup.

34. The method of claim 27, wherein the first backup is an incremental backup.

35. The method of claim 27, wherein the file enables restoring the second backup prior to restoring the first backup without performing substantial duplicative write operations.

36. A computer-readable storage medium, comprising:

a first computer-executable instruction operable to create a first backup of at least a portion of a plurality of data blocks, the first backup comprising a copy of at least a portion of the plurality of data blocks;

a second computer-executable instruction operable to create, after creating the first backup, a second backup of at least a portion of the plurality of data blocks, the second backup comprising a copy of at least a portion of the plurality of data blocks;

a third computer-executable instruction operable to identify, by comparing the second backup with the first backup, one or more data blocks within the second backup to be restored in place of corresponding data blocks within the first backup during a reverse-chronological restore operation;

a fourth computer-executable instruction operable to create a file that identifies each data block within the second backup that is to be restored in place of corresponding data blocks within the first backup during the reverse-chronological restore operation; and

a fifth computer-executable instruction operable to store the file.

37. The computer-readable medium of claim 36, further comprising a fifth computer-executable instruction operable to identify each data block within the second backup that has been modified since creation of the first backup.

38. The computer-readable medium of claim 36, wherein the reverse-chronological restore operation comprises a restore operation in which the second backup is restored prior to restoring the first backup.

39. The computer-readable medium of claim 36, wherein the file comprises a bitmap that comprises at least one bit for each data block within the second backup that is to be restored in place of corresponding data blocks within the first backup during the reverse-chronological restore operation.