Storage system snapshots for continuous file protection

• US 8,046,547 B1
• Filed: 01/11/2008
• Issued: 10/25/2011
• Est. Priority Date: 01/30/2007
• Status: Active Grant

• Current Assignee: AmZetta Technologies, LLC (American Megatrends International, LLC)
• Original Assignee: American Megatrends Incorporated
• Inventors: Ganapathy, Narayanaswami, Chatterjee, Paresh, Grandhi, Suresh, Subramanian, Srikumar
• Primary Examiner(s): Dudek, Jr.; Edward J
• Application Number:
  US12/013,099
• Time in Patent Office: 1,383 Days
• Field of Search: 711/162, 711/E12.103, 707/649, 707/657
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1461 Backup scheduling policy
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

Techniques for continuous data protection can include creating snapshots of one or more underlying storage volumes upon specific file system events. Generating snapshots upon every file close event can protect the files in a storage system by keeping a snapshot of every version or modification of each file. Removal of redundant snapshots can mitigate the impact on storage capacity associated with creating these large numbers of volume snapshots upon each file close event. Additionally, file closure lists can be employed to allow generating snapshots only when a previously closed file is reopened. Such an approach can protect the previous version of a file prior to the opening of a new version of the file. Such an approach can also mitigate storage capacity impact without the creation of redundant snapshots.

Claims

1. A method for providing continuous data protection, the method comprising:

trapping a file system call;

evaluating if the trapped file system call is associated with a file that has been modified;

generating a storage snapshot in response to the file having been modified;

determining if a previous storage snapshot has been rendered redundant by generating the storage snapshot; and

deleting the previous storage snapshot if the previous storage snapshot has been rendered redundant.

2. The method of claim 1, further comprising providing a file closure list.

3. The method of claim 2, further comprising adding the file to the file closure list if the trapped file system call is a file close operation.

4. The method of claim 2, wherein evaluating if the trapped file system call is associated with the file that has been modified comprises determining that the trapped call is a file open operation while the file is in the file closure list.

5. The method of claim 2, further comprising clearing the file closure list after generating the snapshot.

6. The method of claim 1, wherein evaluating if the trapped file system call is associated with the file that has been modified comprises determining that the trapped call is a file close operation.

7. A method for providing continuous data protection, the method comprising:

trapping a file system call;

evaluating if the trapped file system call is associated with a file that has been modified;

generating a storage snapshot in response to the file having been modified;

determining if a previous storage snapshot has been rendered redundant by generating the storage snapshot,

wherein determining that the previous storage snapshot has been rendered redundant comprises identifying that a version of a file protected by the previous storage snapshot is also protected by generating the storage snapshot.

8. A computer storage medium having computer-executable instructions stored thereon which, when executed by a computer system, cause the computer system to:

trap a file system call;

evaluate if the trapped file system call is associated with a file that has been modified;

generate a storage snapshot in response to the file having been modified;

determine if a previous storage snapshot has been rendered redundant by generating the storage snapshot; and

causing the computer system to delete the previous storage snapshot if the previous storage snapshot has been rendered redundant.

9. The computer storage medium of claim 8, further comprising causing the computer system to provide a file closure list.

10. The computer storage medium of claim 9, further comprising causing the computer system to add the file to the file closure list if the trapped file system call is a file close operation.

11. The computer storage medium of claim 9, wherein evaluating if the trapped file system call is associated with the file that has been modified comprises determining that the trapped call is a file open operation while the file is in the file closure list.

12. The computer storage medium of claim 9, further comprising causing the computer system to clear the file closure list after generating the snapshot.

13. The computer storage medium of claim 8, wherein evaluating if the trapped file system call is associated with the file that has been modified comprises determining that the trapped call is a file close operation.

14. A computer storage medium having computer-executable instructions stored thereon which, when executed by a computer system, cause the computer system to:

trap a file system call;

evaluate if the trapped file system call is associated with a file that has been modified;

generate a storage snapshot in response to the file having been modified; and

determine if a previous storage snapshot has been rendered redundant by generating the storage snapshot,

wherein determining that the previous storage snapshot has been rendered redundant comprises identifying that a version of a file protected by the previous storage snapshot is also protected by generating the storage snapshot.