Responding to a failure of a storage system

• US 7,752,492 B1
• Filed: 05/25/2007
• Issued: 07/06/2010
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Kilian, Michael, Todd, Stephen J., Armangau, Philippe
• Primary Examiner(s): Maskulinski; Michael C
• Application Number:
  US11/807,070
• Time in Patent Office: 1,138 Days
• Field of Search: None
• US Class Current: 714/6.13
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/2084 on the same storage unit
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

Aspects of the invention relate to creating a snapshot of a file system on an OAS system. A snapshot of a file system is an image of a file system at a particular point in time. A snapshot of a file system may be used to restore the file system to its state at the time of creation of the snapshot in, for example, situations where the file system has become corrupted.

Claims

1. A method of processing content in a computer system comprising at least one storage device that stores a plurality of content units each identified by an object identifier, the method comprising an act of:

(A) in response to a failure in the computer system that results in a loss of at least some of the plurality of content units caused, at least in part, by a loss of metadata identifying a storage location on the least one storage device for the lost content units, providing the object identifier for each of the lost content units.

2. The method of claim 1, wherein the computer system comprises at least one object addressable storage (OAS) system, and wherein the at least one storage device is disposed in the at least one (OAS) system, the at least one OAS system having an OAS layer that receives OAS access requests from an application program.

3. The method of claim 1, wherein the object identifier for each content unit is a content address that is generated, at least in part, based on at least a portion of the content of the content unit.

4. The method of claim 2, wherein the OAS system includes a file system, and wherein the failure that results in a loss of the at least some of the plurality of content units comprises a corruption of the file system.

5. The method of claim 4, further comprising an act of:

(B) restoring the file system from a previously-created snapshot of the file system.

6. The method of claim 5, wherein lost content units are content units stored on the least one storage device after creation of the previously-created snapshot.

7. At least one computer readable medium encoded with instructions that, when executed, perform a method of processing content in a computer system comprising at least one storage device that stores a plurality of content units each identified by an object identifier, the method comprising an act of:

(A) in response to a failure in the computer system that results in a loss of at least some of the plurality of content units caused, at least in part, by a loss of metadata identifying a storage location on the least one storage device for the lost content units, providing the object identifier for each of the lost content units.

8. The at least one computer readable medium of claim 7, wherein the computer system comprises at least one object addressable storage (OAS) system, and wherein the at least one storage device is disposed in that at least one (OAS) system, the at least one OAS system having an OAS layer that receives OAS access requests from an application program.

9. The at least one computer readable medium of claim 7, wherein the object identifier for each content unit is a content address that is generated, at least in part, based on at least a portion of the content of the content unit.

10. The at least one computer readable medium of claim 8, wherein the OAS system includes a file system, and wherein the failure that results in a loss of the at least some of the plurality of content units comprises a corruption of the file system.

11. The at least one computer readable medium of claim 10, wherein the method further comprises an act of:

(B) restoring the file system from a previously-created snapshot of the file system.

12. The at least one computer readable medium of claim 11, wherein lost content units are content units stored on the least one storage device after creation of the previously-created snapshot.

13. A computer system comprising:

at least one storage device that stores a plurality of content units each identified by an object identifier; and

at least one controller that;

in response to a failure in the computer system that results in a loss of at least some of the plurality of content units caused, at least in part, by a loss of metadata identifying a storage location on the least one storage device for the lost content units, provides the object identifier for each of the lost content units.

14. The computer system of claim 13, wherein the computer system further comprises at least one object addressable storage (OAS) system, and wherein the at least one storage device and the at least one controller are disposed in that at least one (OAS) system, the at least one OAS system having an OAS layer that receives OAS access requests from an application program.

15. The computer system of claim 13, wherein the object identifier for each content unit is a content address that is generated, at least in part, based on at least a portion of the content of the content unit.

16. The computer system of claim 14, wherein the OAS system includes a file system, and wherein the failure that results in a loss of the at least some of the plurality of content units comprises a corruption of the file system.

17. The computer system of claim 16, wherein the at least one controller restores the file system from a previously-created snapshot of the file system.