Space reclamation with virtually provisioned devices

• US 8,959,305 B1
• Filed: 06/29/2012
• Issued: 02/17/2015
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Lecrone, Douglas E., Linstead, Paul A., Pocock, Bruce
• Primary Examiner(s): Choe, Yong
• Assistant Examiner(s): GIARDINO JR, MARK A
• Application Number:
  US13/537,345
• Time in Patent Office: 963 Days
• Field of Search: 707/813, 711/166, 718/104
• US Class Current: 711/166
• CPC Class Codes: G06F 12/023 Free address space management

Abstract

A reclaim system provides for marking each track that is intended to be reclaimed in one or more storage devices and detecting and reclaiming such tracks. The reclaim system may include a feature and/or utility that may be used to mark, detect and return tracks to a free track pool of a virtual provisioning storage system in connection with the use of one or more thin Count Key Data (CKD) devices. Reclaim processing may include identifying tracks to be reclaimed, marking mark the tracks to be reclaimed, detecting tracks that have been marked to be reclaimed, and performing a reclaim task to return the marked and detected tracks to the free track pool, thereby reclaiming the tracks.

Claims

1. A method for performing reclaim processing of a storage system with virtually provisioned devices, comprising:

identifying at least one track corresponding to a virtually provisioned device of the storage system that is a candidate for reclaiming, wherein the at least one track is virtually provisioned to the virtually provisioned device but for which no requirement exists that the at least one track is backed by physical storage of the storage system;

marking the at least one track, as a marked track, wherein the marked track is marked using at least one bit that is independent of any current data content corresponding to the marked track, and wherein setting of the at least one bit does not reflect whether the marked track is backed by physical storage;

detecting the marked track; and

reclaiming the marked track to a free track pool of the storage system.

2. The method according to claim 1, wherein identifying the at least one track includes executing a session for one or more of the virtually provisioned devices that scans the one or more virtually provisioned devices and monitors changes in data on the one or more virtually provisioned devices.

3. The method according to claim 2, wherein the session maintains a map having at least one bit for each track of the one or more of the virtually provisioned devices that identifies the tracks as candidates for reclaiming.

4. The method according to claim 1, wherein marking the at least one track includes performing a track erase command on the at least one track that marks the track as erased.

5. The method according to claim 4, wherein the marked track that is marked as erased includes a record zero written to the at least one bit.

6. The method according to claim 1, further comprising:

scheduling the reclaim processing using at least one utility.

7. The method according to claim 6, wherein the scheduling includes automatically scheduling the performing of the reclaim processing as a background task.

8. The method according to claim 1, wherein the virtually provisioned device includes a count key data device.

9. A non-transitory computer readable medium storing software for performing reclaim processing of a storage system with virtually provisioned devices, the software comprising:

executable code that identifies at least one track corresponding to a virtually provisioned device of the storage system that is a candidate for reclaiming, wherein the at least one track is virtually provisioned to the virtually provisioned device but for which no requirement exists that the at least one track is backed by physical storage of the storage system;

executable code that marks the at least one track, as a marked track, wherein the marked track is marked using at least one bit that is independent of any current data content corresponding to the marked track, and wherein setting of the at least one bit does not reflect whether the marked track is backed by physical storage;

executable code that detects the marked track; and

executable code that reclaims the marked track to a free track pool of the storage system.

10. The non-transitory computer readable medium according to claim 9, wherein the executable code that identifies the at least one track includes executable code that executes a session for one or more of the virtually provisioned devices and executable code that scans the one or more virtually provisioned devices and monitors changes in data on the one or more virtually provisioned devices.

11. The non-transitory computer readable medium according to claim 10, wherein the executable code that executes the session includes executable code that maintains a map having at least one bit for each track of the one or more of the virtually provisioned devices that identifies the tracks as candidates for reclaiming.

12. The non-transitory computer readable medium according to claim 9, wherein the executable code that marks the at least one track includes executable code that performs a track erase command on the at least one track that marks the track as erased.

13. The non-transitory computer readable medium according to claim 12, wherein the marked track that is marked as erased includes a record zero written to the at least one bit.

14. The non-transitory computer readable medium according to claim 9, further comprising:

executable code that schedules the reclaim processing using at least one utility.

15. The non-transitory computer readable medium according to claim 14, wherein the scheduling includes automatically scheduling the performing of the reclaim processing as a background task.

16. The non-transitory computer readable medium according to claim 9, wherein the virtually provisioned device includes a count key data device.

17. A system for performing reclaim processing, comprising:

at least one virtually provisioned device of a storage system;

at least one utility that performs reclaim processing on the at least one virtually provisioned device, the at least one utility including software stored on a non-transitory computer readable medium storing software, the software comprising;

executable code that identifies at least one track corresponding to a virtually provisioned device of the storage system that is a candidate for reclaiming, wherein the at least one track is virtually provisioned to the virtually provisioned device but for which no requirement exists that the at least one track is backed by physical storage of the storage system;

executable code that marks the at least one track, as a marked track, wherein the marked track is marked using at least one bit that is independent of any current data content corresponding to the marked track, and wherein setting of the at least one bit does not reflect whether the marked track is backed by physical storage;

executable code that detects the marked track; and

executable code that reclaims the marked track to a free track pool of the storage system.

18. The system according to claim 17, wherein the executable code that identifies the at least one track includes executable code that executes a session for one or more of the virtually provisioned devices and executable code that scans the one or more virtually provisioned devices and monitors changes in data on the one or more virtually provisioned devices, wherein the executable code that executes the session maintains a map having at least one bit for each track of the one or more of the virtually provisioned devices that identifies the tracks as candidates for reclaiming, and wherein the executable code that marks the at least one track includes executable code that performs a track erase command on the at least one track that marks the track as erased.

19. The system according to claim 17, further comprising:

executable code that schedules the reclaim processing using the at least one utility.

20. The system according to claim 17, wherein the at least one virtually provisioned device includes a count key data device.