Method and apparatus for recovery of a logical volume in a multi copy storage system

• US 7,080,277 B2
• Filed: 08/29/2002
• Issued: 07/18/2006
• Est. Priority Date: 08/29/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Anna, Josephina, Kishi, Gregory Tad, Gibble, Kevin Lee
• Primary Examiner(s): Iqbal, Nadeem
• Application Number:
  US10/231,359
• Publication Number:
  US 20040078639A1
• Time in Patent Office: 1,419 Days
• Field of Search: 714/2, 714/6, 714/7, 714/13, 714/15, 714/42, 711/162, 711/6, 711/165, 709/214, 709/225
• US Class Current: 714/2
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/1469 Backup restoration techniques

Abstract

A system, apparatus, and method to recover a logical volume on a physical volume, or data storage cartridge, within a dual copy data storage system, such as a virtual tape server (VTS) system. Such recovery follows a disaster situation involving a primary copy of the requested logical volume. The system, apparatus, and method include modules and steps as required to recover a logical volume, or data file or block, through manipulation and swapping of record files, or stubs, that point to primary and secondary copies of a logical volume. Such primary and secondary logical volumes are stored on distinct physical volumes in order to provide quality storage media management and reduce the likelihood of loss of data. The recovery and swapping procedures are implemented in a manner that is substantially transparent to a host or client requires no additional input from the host or client

Claims

1. A data storage apparatus configured to store data from a host on a plurality of physical data storage media devices, the apparatus comprising:

a local data storage cache within a dual copy data storage apparatus;

a primary record stored on the cache;

a secondary record stored on the cache; and

a recovery module configured to implement a recovery action to recover a secondary logical volume in response to a failure to access a primary logical volume.

2. The apparatus of claim 1, wherein the primary record stored on the cache is configured to point to the primary logical volume.

3. The apparatus of claim 1, wherein the secondary record stored on the cache is configured to point to the secondary logical volume.

4. The apparatus of claim 1, wherein the primary record stored on the cache is located in a primary directory.

5. The apparatus of claim 4, wherein the secondary record stored on the cache is located in a secondary directory that is distinct from the primary directory.

6. The apparatus of claim 1, wherein the primary logical volume is stored on a primary physical data storage media device.

7. The apparatus of claim 1, wherein the secondary logical volume is stored on a secondary physical data storage media device.

8. The apparatus of claim 1, wherein the recovery action comprises overwriting the primary record with the secondary record.

9. The apparatus of claim 1, wherein the recovery module is further configured to implement the recovery action in a manner that is substantially transparent to the host.

10. The apparatus of claim 1, wherein the primary logical volume and the secondary logical volume are assigned an equivalent update level.

11. The apparatus of claim 1, wherein the plurality of physical data storage media devices further comprise tape cartridges.

12. The apparatus of claim 1, wherein the plurality of physical data storage media devices further comprise magnetic disks.

13. The apparatus of claim 1, wherein the plurality of physical data storage media devices further comprise optical disks.

14. The apparatus of claim 1, wherein the primary record and the secondary record are stored in a common directory.

15. A data storage apparatus configured to store data from a host on a plurality of physical data storage media devices, the apparatus comprising:

a local data storage cache within a dual copy data storage apparatus;

a primary logical volume stored on a primary physical data storage media device;

a secondary logical volume stored on a secondary physical data storage media device;

a primary record stored on the cache in a primary directory and configured to point to the primary logical volume;

a secondary record stored on the cache and configured to point to the secondary logical volume;

a recovery module configured to implement a recovery action to recover the secondary logical volume in response to a failure to access the primary logical volume; and

the recovery module further configured to implement the recovery action in a manner that is substantially transparent to the host.

16. A data storage system configured to recover a logical volume, the system comprising:

a dual copy data storage apparatus including a plurality of physical volumes;

a host configured to request data access to a plurality of logical volumes stored on the plurality of physical volumes of the dual copy data storage apparatus;

a recovery module configured to implement a recovery action to recover a secondary logical volume on a secondary physical volume in response to a failure to access a primary logical volume on a primary physical volume; and

the recovery module further configured to implement the recovery action in a manner that is substantially transparent to the host.

17. The system of claim 16, wherein the dual copy data storage apparatus is a virtual tape server.

18. A method for recovering a logical volume in a data storage system, the method comprising:

acknowledging a recall error generated in response to a failure to access a primary logical volume located on a primary physical volume;

accessing a secondary record located on a cache within a dual copy data storage system; and

recovering a secondary logical volume located on a secondary physical volume.

19. The method of claim 18, further comprising overwriting a primary record located on the system cache with the secondary record.

20. The method of claim 19, wherein the primary record is configured to point to the primary logical volume.

21. The method of claim 18, wherein the secondary record is configured to point to the secondary logical volume.

22. The method of claim 18, further comprising verifying that the primary logical volume and secondary logical volume are assigned an equivalent update level.

23. The method of claim 18, wherein recovering the secondary logical volume is performed in a manner that is substantially transparent to a host.

24. The method of claim 18, wherein the dual copy data storage system comprises a host and a virtual tape server.

25. A computer readable medium comprising a computer code configured to carry out a method for recovering a logical volume in a data storage system, the method comprising:

acknowledging a recall error generated in response to a failure to access a primary logical volume located on a primary physical volume;

accessing a secondary record configured to point to the secondary logical volume and located on a cache within a dual copy data storage system;

overwriting a primary record configured to point to the primary logical volume and located on the system cache with the secondary record; and

recovering a secondary logical volume located on a secondary physical volume.

26. A data storage apparatus configured to store data from a host on a plurality of physical data storage media devices, the apparatus comprising:

means for acknowledging a recall error generated in response to a failure to access a primary logical volume located on a primary physical volume;

means for accessing a secondary record located on a cache within a dual copy data storage system;

means for overwriting a primary record located on the system cache with the secondary record; and

means for recovering a secondary logical volume located on a secondary physical volume.