Method and system for recovery of meta data in a storage controller

• US 6,988,171 B2
• Filed: 05/09/2002
• Issued: 01/17/2006
• Est. Priority Date: 03/03/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Martin, Douglas A., Morton, Robert Louis, Todd, Kenneth Wayne, Beardsley, Brent Cameron, Benhase, Michael Thomas
• Primary Examiner(s): BATAILLE, PIERRE MICHE
• Application Number:
  US10/143,119
• Publication Number:
  US 20020138695A1
• Time in Patent Office: 1,349 Days
• Field of Search: 711/161, 711/162, 711/165, 711/154, 711/202, 711/112, 711/113, 714/6, 714/15, 707201-204
• US Class Current: 711/144
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

Disclosed is a method, system, and article of manufacture for processing modified meta data for data recovery operations. The meta data provides information on user data maintained in a storage device. The system determines whether meta data tracks maintained in a cache were modified and indicates in a non-volatile memory that the determined meta data tracks were modified. Data recovery operations may be initiated as a result of a system failure, such as a warmstart or coldstart recovery. During such data recovery operations, the system processes the non-volatile memory and the indications of modified meta data tracks therein to rebuild lost meta data tracks in the cache.

Claims

1. A method for processing modified meta data for data recovery operations, wherein the meta data provides information on customer data maintained in a storage device, comprising:

determining whether meta data tracks maintained in a cache were modified;

indicating in a non-volatile memory that the determined meta data tracks were modified;

initiating a data recovery operation in response to a system failure; and

processing the non-volatile memory and the indications of modified meta data tracks therein to mark as invalid lost meta data tracks in cache to subsequently rebuild the lost metadata tracks during the data recovery operation.

2. The method of claim 1, wherein initiating the data recovery operation comprises:

processing the cache to locate meta data tracks;

determining whether the located meta data tracks in the cache are valid;

discarding the invalid meta data tracks from the cache; and

saving the valid meta data tracks in the cache.

3. The method of claim 1, wherein rebuilding the meta data tracks comprises:

accessing customer data tracks associated with the meta data track;

staging the accessed customer data tracks into cache; and

processing the customer data tracks staged into the cache to rebuild the meta data track.

4. The method of claim 1, wherein the non-volatile memory is a battery backed up random access memory.

5. The method of claim 1, further comprising:

generating a rebuild list from the meta data tracks indicated as modified in the non-volatile memory, wherein the rebuild list is processed to determine the meta data tracks to rebuild.

6. The method of claim 1, further comprising:

receiving an access request for one meta data track after the data recovery operation; and

determining whether the requested meta data track is in the cache, wherein the lost meta data tracks indicated in the non-volatile memory are rebuilt when the lost meta data tracks are not in the cache when requested after the data recovery operation.

7. The method of claim 1, further comprising:

invoking a background process during the data recovery operation, wherein the background process rebuilds the lost metadata tracks indicated in the non-volatile memory.

8. The method of claim 1, further comprising:

determining whether the metadata is in the cache in response to the data recovery operation, wherein the metadata track is lost in response to determining that the metadata is not in the cache; and

creating a track for the metadata in the cache in response to determining that the metadata is not in the cache, wherein the metadata for the created track is marked as invalid.

9. The method of claim 8, further comprising:

determining whether metadata tracks are indicated in the non-volatile memory in response to the data recovery operation, wherein the determination of whether the metadata is in the cache is made with respect to metadata tracks indicated in the non-volatile memory.

10. A system for processing modified meta data for data recovery operations, wherein the meta data provides information on customer data maintained in a storage device, comprising:

a cache;

a non-volatile memory;

means for determining whether meta data tracks maintained in the cache were modified;

means for indicating in the non-volatile memory the determined meta data tracks that were modified;

means for initiating a data recovery operation in response to a system failure; and

means for processing the non-volatile memory and the indications of modified meta data tracks therein to mark as invalid lost meta data tracks in the cache to subsequently rebuild the lost metadata tracks during the data recovery operation.

11. The system of claim 10, wherein the means for initiating the data recovery operation further performs:

processing the cache to locate meta data tracks;

determining whether the located meta data tracks in the cache are valid;

discarding the invalid meta data tracks from the cache; and

saving the valid meta data tracks in the cache.

12. The system of claim 10, wherein the means for rebuilding the meta data tracks further performs:

accessing customer data tracks associated with the meta data track;

staging the accessed customer data tracks into cache; and

processing the customer data tracks staged into the cache to rebuild the meta data track.

13. The system of claim 10, wherein the non-volatile memory is a battery backed up random access memory.

14. The system of claim 10, further comprising:

means for generating a rebuild list from the meta data tracks indicated as modified in the non-volatile memory, wherein the rebuild list is processed to determine the meta data tracks to rebuild.

15. The system of claim 10, further comprising:

means for receiving an access request for one meta data track after the data recovery operation; and

means for determining whether the requested meta data track is in the cache, wherein the lost meta data tracks indicated in the non-volatile memory are rebuilt when the lost meta data tracks are not in the cache when requested after the data recovery operation.

16. The system of claim 10, further comprising:

invoking a background process during the data recovery operation, wherein the background process rebuilds the lost metadata tracks indicated in the non-volatile memory.

17. The system of claim 10, further comprising:

means for determining whether the metadata is in the cache in response to the data recovery operation, wherein the metadata track is lost in response to determining that the metadata is not in the cache; and

means for creating a track for the metadata in the cache in response to determining that the metadata is not in the cache, wherein the metadata for the created track is marked as invalid.

18. The system of claim 17, further comprising:

means for determining whether metadata tracks are indicated in the non-volatile memory in response to the data recovery operation, wherein the determination of whether the metadata is in the cache is made with respect to metadata tracks indicated in the non-volatile memory.

19. An article of manufacture for use in programming a control unit to manage meta data, wherein the meta data provides information on customer data maintained in a storage device, wherein the control unit is in communication with a process, wherein the article of manufacture is capable of causing the control unit to perform:

determining whether meta data tracks maintained in a cache were modified;

indicating in a non-volatile memory that the determined meta data tracks were modified;

initiating a data recovery operation in response to a system failure; and

processing the non-volatile memory and the indications of modified meta data tracks therein to mark as invalid lost meta data tracks in cache to subsequently rebuild the lost metadata tracks during the data recovery operation.

20. The article of manufacture of claim 19, wherein initiating the data recovery operation comprises:

processing the cache to locate meta data tracks;

determining whether the located meta data tracks in the cache are valid;

discarding the invalid meta data tracks from the cache; and

saving the valid meta data tracks in the cache.

21. The article of manufacture of claim 19, wherein rebuilding the meta data tracks comprises:

accessing customer data tracks associated with the meta data track;

staging the accessed customer data tracks into cache; and

processing the customer data tracks staged into the cache to rebuild the meta data track.

22. The article of manufacture of claim 19, wherein the non-volatile memory is a battery backed up random access memory.

23. The article of manufacture of claim 19, further comprising:

generating a rebuild list from the meta data tracks indicated as modified in the non-volatile memory, wherein the rebuild list is processed to determine the meta data tracks to rebuild.

24. The article of manufacture of claim 19, further comprising:

receiving an access request for one meta data track after the data recovery operation; and

determining whether the requested meta data track is in the cache, wherein the lost meta data tracks indicated in the non-volatile memory are rebuilt when the lost meta data tracks are not in the cache when requested after the data recovery operation.

25. The article of manufacture of claim 19, further comprising:

invoking a background process during the data recovery operation, wherein the background process rebuilds the lost metadata tracks indicated in the non-volatile memory.

26. The article of manufacture of claim 19, further comprising:

determining whether the metadata is in the cache in response to the data recovery operation, wherein the metadata track is lost in response to determining that the metadata is not in the cache; and

creating a track for the metadata in the cache in response to determining that the metadata is not in the cache, wherein the metadata for the created track is marked as invalid.

27. The article of manufacture of claim 26, further comprising:

determining whether metadata tracks are indicated in the non-volatile memory in response to the data recovery operation, wherein the determination of whether the metadata is in the cache is made with respect to metadata tracks indicated in the non-volatile memory.