SNAPSHOT RESET METHOD AND APPARATUS

• US 20080320258A1
• Filed: 06/25/2007
• Published: 12/25/2008
• Est. Priority Date: 06/25/2007
• Status: Active Grant

• Current Assignee: Dot Hill Systems Corporation (Seagate Technology Holdings Plc)
• Original Assignee: Dot Hill Systems Corporation (Seagate Technology Holdings Plc)
• Inventors: Lee, Kent, Wayda, James George, Rodriguez, Elizabeth G., Vu, Ngoclan Thi
• Granted Patent: US 8,204,858 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A method, device, and system for resetting snapshots are provided. The reset of a snapshot incorporates the traditional snapshot delete and snapshot create operations into a single operation. Additionally, a snapshot created under the reset operation may receive an array partition from a snapshot being deleted under the same snapshot reset operation thereby retaining its identifying characteristics.

Claims

1. A method, comprising:

receiving a command to reset a first snapshot of a master volume, wherein the first snapshot comprises a first array partition and first snapshot data;

disassociating the first array partition from the first snapshot;

associating the first array partition with second snapshot data of the master volume to create a second snapshot; and

updating the first array partition to reflect at least one characteristic of the master volume at a point-in-time associated with the second snapshot.

2. The method of claim 1, further comprising:

marking the first snapshot for reset;

after marking the first snapshot for reset, marking the first snapshot for deletion;

after the second snapshot has been associated with the first array partition, releasing the reset mark associated with the first snapshot; and

deleting the first snapshot.

3. The method of claim 2, further comprising allowing access to the first snapshot data while the first snapshot is marked for reset.

4. The method of claim 1, wherein the second snapshot is a new snapshot created in response to receiving the reset command.

5. The method of claim 4, wherein the second snapshot is created with a corresponding snapshot data structure and without an array partition.

6. The method of claim 1, wherein the second snapshot is a snapshot that existed prior to receiving the reset command.

7. The method of claim 1, further comprising updating the age of the second snapshot to correspond to the point-in-time when the reset command was received.

8. The method of claim 1, wherein the second snapshot is assigned to at least one of the same global identifier, LUN, Serial Number, and zoning of the LUN that the first snapshot was previously assigned to.

9. A device for controlling a storage system, comprising:

a reset application adapted to receive a reset command and in response to receiving a reset command and to transfer a first array partition associated with first snapshot of a master volume to a second snapshot of the master volume, wherein the first array partition provides access to a virtual disk drive which can at least one of read and write fixed memory block addresses.

10. The device of claim 9, wherein the virtual disk drive is adapted to at least one of read and write fixed blocks addressed by Logical Block Addresses (LBAs).

11. The device of claim 9, wherein the first array partition comprises a first set of attributes that remain unchanged when the first array partition is transferred from the first snapshot to the second snapshot.

12. The device of claim 11, wherein the first set of attributes comprise at least one of a global identifier, LUN, Serial Number, and zoning on the LUN.

13. The device of claim 9, wherein the reset application is further adapted to alter the first array partition to reflect a size of the master volume at a point-in-time associated with the second snapshot.

14. The device of claim 9, wherein the reset application is adapted to mark the first snapshot for reset, then mark the first snapshot for deletion, and then after the first array partition has been associated with the second snapshot, release the reset mark associated with the first snapshot thereby allowing the first snapshot to be deleted.

15. The device of claim 9, wherein the reset application is further adapted to create the second snapshot in response to receiving the reset command.

16. A data storage system, comprising:

means for receiving a command to reset a first snapshot of a master volume, wherein the first snapshot comprises a first array partition and first snapshot data;

means for transferring the first array partition from the first snapshot to a second snapshot of the master volume, wherein the second snapshot corresponds to a point-in-time later than the first snapshot; and

means for updating the first array partition to reflect a characteristic of the master volume at the point-in-time associated with the second snapshot.

17. The system of claim 16, wherein the means for transferring comprises:

means for disassociating the first array partition from the first snapshot; and

means for associating the first array partition with the second snapshot of the master volume.

18. The system of claim 17, further comprising:

means for marking the first snapshot for reset;

means for marking the first snapshot for deletion; and

means for deleting the first snapshot, wherein the means for deleting is restricted from deleting the first snapshot while the means for marking the first snapshot for reset has the first snapshot affirmatively marked for reset.

19. The system of claim 18, wherein the means for marking the first snapshot for reset is adapted to release the mark indicating that the first snapshot is being reset in response to determining that the means for associating has associated with the first array partition with the second snapshot.

20. The system of claim 16, further comprising means for creating the second snapshot in response to determining that the means for receiving has receiving the command to reset the first snapshot.