Restoring data from point-in-time representations of the data

• US 20040172577A1
• Filed: 02/27/2003
• Published: 09/02/2004
• Est. Priority Date: 02/27/2003
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Tan, Choon-Seng, Pellegrino, Greg J., Natrajan, Balaji
• Granted Patent: US 7,231,544 B2
• Time in Patent Office: Days
• US Class Current: 714/13
• CPC Class Codes: G06F 11/1446 Point-in-time backing up or restoration of persistent data
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A system includes a controller to store point-in-time representations (or snapshots) of data taken at different time points from storage unit of a storage subsystem. Data can be restored from one of the point-in-time representations, with point-in-time representations taken later than the one point-in-time representation maintained enabled to allow a subsequent restoring of data from the later point-in-time representations.

Claims

1. A method for use in a system, comprising:

storing plural point-in-time representations of data taken at plural respective time points from a storage unit;

receiving a first request to restore data from a first one of the point-in-time representations; and

in response to the first request to restore but prior to performing the restore, storing data in the storage unit in another point-in-time representation.

2. The method of claim 1, wherein storing the point-in-time representations of data taken from the storage unit comprises storing the point-in-time representations of data taken from a logical storage volume.

3. The method of claim 1, further comprising restoring data into the storage unit from the first one of the point-in-time representations.

4. The method of claim 3, further comprising receiving a second request to restore data from a second one of the point-in-time representations that is subsequent to the first one point-in-time representation;

and

in response to the second request, restoring data into the storage unit from the second one of the point-in-time representations.

5. The method of claim 3, further comprising restoring data into the storage unit from the another point-in-time representation to restore the storage unit back to a state prior to the restore that is performed in response to the first request.

6. The method of claim 1, further comprising storing other point-in-time representations taken at time points prior to the first one of the point-in-time representations.

7. The method of claim 1, further comprising:

restoring data into the storage unit from the first one of the point-in-time representations; and

maintaining enabled point-in-time representations subsequent to the first one of the point-in-time representations.

8. The method of claim 7, wherein maintaining enabled point-in-time representations comprises maintaining corresponding indicators at an active state.

9. The method of claim 1, wherein storing the plural point-in-time representations comprises storing the plural point-in-time representations in a storage region of a storage subsystem separate from a region of the storage subsystem containing the storage unit.

10. The method of claim 9, further comprising storing information to identify locations of the point-in-time representations.

11. The method of claim 10, further comprising storing an indicator for each point-in-time representation to indicate whether the point-in-time representation is enabled or disabled.

12. An article comprising at least one storage medium containing instructions that when executed cause a system to:

store plural point-in-time representations of data taken at respective time points from a storage unit;

perform a restore from a first one of the point-in-time representations; and

maintain other point-in-time representations enabled to allow a subsequent restore of data from a second one of the point-in-time representations taken subsequently to the first one of the point-in-time representations.

13. The article of claim 12, wherein the instructions when executed cause the system to further restore data into the storage unit from the first one of the point-in-time representations.

14. The article of claim 13, wherein the instructions when executed cause the system to further:

receive a second request to restore data from the second one of the point-in-time representations that is subsequent to the first one point-in-time representation; and

in response to the second request, restore data into the storage unit from the second one of the point-in-time representations.

15. The article of claim 12, wherein the instructions when executed cause the system to further:

receive a request to perform the restore from the first point-in-time representation; and

in response to the request but prior to performing the restore, copy content of the storage unit into a currently active point-in-time representation.

16. The article of claim 12, wherein the instructions when executed cause the system to further:

store information to identify locations of the point-in-time representations, and to indicate whether each point-in-time representation is enabled or disabled.

17. A system comprising:

a storage containing a storage unit, plural point-in-time representations of the storage unit, and an indicator; and

a controller adapted to perform one of a single-direction restore and a dual-direction restore from the point-in-time representations based on a state of the indicator.

18. The system of claim 17, wherein the controller performs the single-direction restore by:

restoring data from one of the point-in-time representations into the storage unit; and

disabling point-in-time representations subsequent to the one point-in-time representation.

19. The system of claim 18, wherein the controller performs the single-direction restore by further:

maintaining enabled point-in-time representations prior to the one point-in-time representation.

20. The system of claim 17, wherein the controller performs the dual-direction restore by:

restoring data from one of the point-in-time representations into the storage unit; and

maintaining enabled point-in-time representations subsequent to the one point-in-time representation.

21. The system of claim 20, wherein the controller performs the dual-direction restore by further:

receiving a request to perform the restore from the one point-in-time representation; and

in response to the request and prior to restoring data from the one point-in-time representation, copying data in the storage unit into another point-in-time representation.

22. A controller for controlling a storage subsystem, comprising:

a data access module to store data in a logical storage unit of the storage subsystem; and

a snapshot module to;

store plural snapshots of data taken at plural corresponding time points;

receive a first request to restore data from one of the snapshots; and

in response to the first request but prior to performing the restore, copy data in the logical storage unit to another snapshot.

23. The controller of claim 22, the snapshot module to further:

perform a first restore of data from the one snapshot in response to the first request; and

in response to another request, perform a second restore of data from the another snapshot to restore a state of the logical storage unit prior to the first restore.

24. A system comprising:

means for storing plural snapshots of data taken at respective plural time points;

means for restoring a first one of the snapshots; and

means for maintaining other snapshots enabled to allow a subsequent restore of data from a second one of the snapshots taken subsequently to the first one of the snapshots.

25. The system of claim 24, further comprising means for storing indicators to indicate whether corresponding snapshots are enabled or disabled.