Writable snapshots for boot consolidation

• US 8,082,407 B1
• Filed: 04/16/2008
• Issued: 12/20/2011
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: AmZetta Technologies, LLC (American Megatrends International, LLC)
• Original Assignee: American Megatrends Incorporated
• Inventors: Chatterjee, Paresh, Ganapathy, Narayanaswami, Jayaraman, Raja, Narayanan, Ajit
• Primary Examiner(s): Farrokh, Hashem
• Application Number:
  US12/104,116
• Time in Patent Office: 1,343 Days
• Field of Search: 711/162, 707/639
• US Class Current: 711/162
• CPC Class Codes: G06F 9/4416 Network booting; Remote initial program loading [RIPL]

Abstract

Boot consolidation based on writeable volume snapshots can leverage flexible mappings of snapshot dependencies. Such flexible mappings can be established by relating sequence numbers associated with various volume snapshots and can provide for an arbitrarily complex mapping to support a potentially unlimited number of writable snapshots in potentially any dependency configuration. Additionally, the pinning of volumes can provide support for chains of snapshots to depend from snapshots within other chains of snapshots. Merge agents can operate with writable snapshots and boot consolidation to provide system-wide updates where security patches, upgrades, and application software may be applied to a group of servers or a group of users in an efficient fashion.

Claims

1. A system for boot consolidation comprising:

a storage subsystem;

a physical storage device associated with the storage subsystem;

a plurality of volume snapshots stored on the physical storage device, each one of the plurality of volume snapshots associated with a respective one of a plurality of initiators;

one or more modules operable to cause the storage subsystem to provide each one of the plurality of initiators access to the respective associated one of the plurality of volume snapshots for booting from;

one or more modules operable to cause the storage subsystem to create a read-only snapshot from one of the plurality of volume snapshots, wherein each one of the plurality of volume snapshots is a writable snapshot, and

one or more modules operable to cause the storage subsystem to provide a data structure for maintaining volume snapshot dependencies, the data structure providing for arbitrary dependencies between the read-only snapshot and the one of the plurality of volume snapshots.

2. The system of claim 1, wherein each one of the plurality of volume snapshots is a snapshot of a common parent snapshot.

3. The system of claim 1, further comprising one or more modules operable to cause the storage subsystem to pin one of the plurality of volume snapshots to one of a second plurality of volume snapshots wherein pinning creates a snapshot dependency.

4. The system of claim 1, further comprising one or more modules operable to cause the system to create a writable snapshot, apply system upgrades to the writable snapshot, and propagate the upgrades to a plurality of snapshots to be upgraded.

5. A method for managing volume snapshots using dependency mapping, the method comprising:

providing a data structure for maintaining volume snapshot dependencies, the data structure providing for arbitrary dependencies between read-only and writeable snapshots;

adding a dependency to the data structure in response to a snapshot being created;

determining a chain of snapshot dependency from the data structure; and

traversing the chain of snapshot dependency to determine physical locations for data storage operations.

6. The method of claim 5, wherein the snapshot dependencies relate to snapshots used for boot consolidation.

7. The method of claim 5, wherein the snapshot dependencies each relate a sequence number of a first snapshot to the sequence number of a second snapshot, the first snapshot depending from the second snapshot.

8. The method of claim 5, wherein two or more of the snapshot dependencies indicate the dependency of two or more snapshots from a common parent snapshot.

9. The method of claim 5, wherein one of the snapshot dependencies indicates the dependency of a read-only snapshot from a writable snapshot.

10. The method of claim 5, wherein one of the snapshot dependencies indicates the dependency of a writable snapshot from a read-only snapshot.

11. The method of claim 5, further comprising a data structure for maintaining a volume pinning relationship between a first snapshot associated with a first volume to a second snapshot associated with a second volume.

12. The method of claim 11, wherein a chain of snapshot dependency including the second snapshot also includes the first snapshot.

13. A method for system-wide updates, the method comprising:

providing a writable snapshot system;

generate a writable snapshot;

applying an update to the writable snapshot;

creating delta information associated with the update; and

propagating the update to a plurality of snapshots to be updated, the propagating comprising;

determining if the update can be applied automatically;

automatically applying the update in response to determining that the update can be applied automatically; and

generating a notification requesting manual intervention in response to determining that the update cannot be applied automatically.

14. The method of claim 13, wherein the writable snapshot is a control snapshot created from a common parent snapshot of the plurality of snapshots to be updated.

15. The method of claim 14, wherein the delta information contains differences between the updated control snapshot and the common parent snapshot;

and propagating the update comprises applying the delta information to the plurality of snapshots to be updated.

16. The method of claim 13, wherein the writable snapshot is a snapshot of a common parent snapshot of the plurality of snapshots to be updated.

17. The method of claim 16, wherein the delta information contains differences between each of the plurality of snapshots to be updated and the common parent snapshot;

propagating the update comprises, for each one of the plurality of snapshots to be updated, generating an updatable snapshot of the writable snapshot and applying the respective delta information to the updatable snapshot.