Method, system, and program for storing and using metadata in multiple storage locations

• US 20060106898A1
• Filed: 11/17/2004
• Published: 05/18/2006
• Est. Priority Date: 11/17/2004
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ripberger, Richard Anthony, Vageline, Michael P., Frondozo, Rhea Reyes, Sheppard, Jacob Lee, Lovrien, Kurt Allen
• Granted Patent: US 7,444,360 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/2056 by mirroring
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

Provided are a method, system, and program for storing and using metadata in multiple storage location. Signature data is stored in a system storage indicating a plurality of metadata copy locations, each locating identifying a storage device and a copy location within the storage device. Each location contains one copy of the metadata, wherein the metadata includes system configuration information. A copy of the signature data is stored with each copy of the metadata.

Claims

1. A method, comprising:

storing signature data in a system storage indicating a plurality of metadata copy locations, each locating identifying a storage device and a copy location within the storage device, wherein each location contains one copy of the metadata, wherein the metadata includes system configuration information; and

storing a copy of the signature data with each copy of the metadata.

2. The method of claim 1, wherein the location of the storage devices to store the copies of the metadata are selected to minimize a number of points of failure.

3. The method of claim 1, further comprising:

initiating an operation to alter the locations of the metadata copies in the storage devices storing the metadata;

determining new locations in the storage devices for the metadata; and

updating each copy of the signature data to indicate the new locations for the metadata; and

copy metadata and the updated signature data to any of the new locations that do not already include metadata and signature data.

4. The method of claim 3, wherein the locations within the signature data comprises an ordered set, wherein the signature data is updated at the locations in an order according to the ordered set.

5. The method of claim 3, wherein the determination of the new location is made in response to a change in the set of storage devices and wherein the determination of the new location is performed in order to minimize a number of points of failure for the changed set of the storage devices.

6. The method of claim 1, wherein two processing systems are capable of accessing the metadata and signature data in the storage devices, and wherein each processing system has a computer readable medium including a copy of the signature data.

7. The method of claim 6, further comprising:

receiving an update to the metadata; and

serially copying the update to the metadata in the storage devices according to an ordering of the storage device locations indicated in the signature data.

8. The method of claim 6, further comprising:

receiving a request to read the metadata;

accessing the metadata in the storage locations until one valid copy of the metadata is found; and

updating copies of the metadata determined to be invalid with the accessed valid copy of the metadata.

9. The method of claim 1, wherein each copy of the signature data includes a generation number, further comprising:

incrementing the generation number in each copy of the signature data in response to changing the locations in which the copy of the metadata is included.

10. The method of claim 9, wherein a first and second processing systems are capable of accessing the metadata and signature data in the storage devices, and wherein the first processing system and second processing system maintain a first and second copy of the signature data, respectively, further comprising:

performing an initialization by the first processing system;

determining a validity of one of the accessible signature data on the storage devices or processing system;

staying off line in response to determining that no signature data is valid; and

updating all accessible copies of the signature data in the metadata locations indicated in the validated signature data and the first and second copies of the signature data with the validated copy of the signature data.

11. The method of claim 10, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that matches the first and second copies of the signature data or validating one storage device signature data that has a generation number one greater than the generation number of the matching first and second copies of the signature data and where the one storage device signature data and the first and second copies of the signature data identify a common storage device.

12. The method of claim 10, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that has a generation number equal to or one greater than a largest generation number of the first and second copies of the signature data in response to determining that the generation numbers of the first and second copies of the signature data do not match and that the first and second copies of the signature data identify the validated storage device.

13. The method of claim 10, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that has a generation number greater by one or equal to the generation number in one of the first and second copies of the signature data in response to determining that signature data in the storage devices identifies the storage devices.

14. A system, comprising:

a plurality of storage devices

a processing system having a system storage and in communication with the storage devices; and

a computer readable medium including code executed by the processing system to perform operations comprising;

(i) storing signature data in the system storage indicating a plurality of metadata copy locations, each locating identifying a storage device and a copy location within the storage device, wherein each location contains one copy of the metadata, wherein the metadata includes system configuration information; and

(ii) storing a copy of the signature data with each copy of the metadata.

15. The system of claim 14, wherein the locations of the storage devices to store the copies of the metadata are selected to minimize a number of points of failure.

16. The system of claim 14, wherein the operations caused by the code further comprises:

initiating an operation to alter the locations of the metadata copies in the storage devices storing the metadata;

determining new locations in the storage devices for the metadata; and

updating each copy of the signature data to indicate the new locations for the metadata; and

copy metadata and the updated signature data to any of the new locations that do not already include metadata and signature data.

17. The system of claim 16, wherein the locations within the signature data comprises an ordered set, wherein the signature data is updated at the locations in an order according to the ordered set.

18. The system of claim 17, wherein the determination of the new location is made in response to a change in the set of storage devices and wherein the determination of the new location is performed in order to minimize a number of points of failure for the changed set of the storage devices.

19. The system of claim 14, wherein the processing system comprises a first processing system, further comprising:

a second processing system, wherein both processing systems are capable of accessing the metadata and signature data in the storage devices, and wherein each processing system has a local storage including a copy of the signature data.

20. The system of claim 19, wherein the code further causes operations comprising:

receiving an update to the metadata; and

serially copying the update to the metadata in the storage devices according to an ordering of the storage device locations indicated in the signature data.

21. The system of claim 19, wherein the code further causes operations comprising:

receiving a request to read the metadata;

accessing the metadata in the storage locations until one valid copy of the metadata is found; and

updating copies of the metadata determined to be invalid with the accessed valid copy of the metadata.

22. The system of claim 16, wherein each copy of the signature data includes a generation number, wherein the code further causes operations comprising:

incrementing the generation number in each copy of the signature data in response to changing the locations in which the copy of the metadata is included.

23. The system of claim 22, wherein the processing system comprises a first processing system, further comprising:

a second processing system, wherein both processing systems are capable of accessing the metadata and signature data in the storage devices, and wherein each processing system has a local storage including a copy of the signature data;

wherein the code is executed by the first processing to further perform;

(i) performing an initialization by the first processing system;

(ii) determining a validity of one of the accessible signature data on the storage devices or processing system;

(iii) staying off line in response to determining that no signature data is valid; and

(iv) updating all accessible copies of the signature data in the metadata locations indicated in the validated signature data and the first and second copies of the signature data with the validated copy of the signature data.

24. The system of claim 23, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that matches the first and second copies of the signature data or validating one storage device signature data that has a generation number one greater than the generation number of the matching first and second copies of the signature data and where the one storage device signature data and the first and second copies of the signature data identify a common storage device.

25. The system of claim 23, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that has a generation number equal to or one greater than a largest generation number of the first and second copies of the signature data in response to determining that the generation numbers of the first and second copies of the signature data do not match and that the first and second copies of the signature data identify the validated storage device.

26. The system of claim 23, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that has a generation number greater by one or equal to the generation number in one of the first and second copies of the signature data in response to determining that signature data in the storage devices identifies the storage devices.

27. An article of manufacture in communication with a plurality of storage devices and a system storage, wherein the article of manufacture includes code that is capable of causing operations to be performed, the operations comprising:

storing signature data in the system storage indicating a plurality of metadata copy locations, each locating identifying one storage device and a copy location within the storage device, wherein each location contains one copy of the metadata, wherein the metadata includes system configuration information; and

storing a copy of the signature data with each copy of the metadata.

28. The article of manufacture of claim 27, wherein the location of the storage devices to store the copies of the metadata are selected to minimize a number of points of failure.

29. The article of manufacture of claim 27, wherein the operations further comprise:

initiating an operation to alter the locations of the metadata copies in the storage devices storing the metadata;

determining new locations in the storage devices for the metadata; and

updating each copy of the signature data to indicate the new locations for the metadata; and

copy metadata and the updated signature data to any of the new locations that do not already include metadata and signature data.

30. The article of manufacture of claim 29, wherein the locations within the signature data comprises an ordered set, wherein the signature data is updated at the locations in an order according to the ordered set.

31. The article of manufacture of claim 29, wherein the determination of the new location is made in response to a change in the set of storage devices and wherein the determination of the new location is performed in order to minimize a number of points of failure for the changed set of the storage devices.

32. The article of manufacture of claim 27, wherein two processing systems are capable of accessing the metadata and signature data in the storage devices, and wherein each processing system has a computer readable medium including a copy of the signature data.

33. The article of manufacture of claim 32, wherein the operations further comprise:

receiving an update to the metadata; and

serially copying the update to the metadata in the storage devices according to an ordering of the storage device locations indicated in the signature data.

34. The article of manufacture of claim 32, wherein the operations further comprise:

receiving a request to read the metadata;

accessing the metadata in the storage locations until one valid copy of the metadata is found; and

updating copies of the metadata determined to be invalid with the accessed valid copy of the metadata.

35. The article of manufacture of claim 27, wherein each copy of the signature data includes a generation number, wherein the operations further comprise:

incrementing the generation number in each copy of the signature data in response to changing the locations in which the copy of the metadata is included.

36. The article of manufacture of claim 35, wherein a first and second processing systems are capable of accessing the metadata and signature data in the storage devices, wherein the first processing system and second processing system maintain a first and second copy of the signature data, wherein the first and second processing systems execute the code, and wherein the operations further comprise:

performing an initialization;

determining a validity of one of the accessible signature data on the storage devices or processing system;

staying off line in response to determining that no signature data is valid; and

updating all accessible copies of the signature data in the metadata locations indicated in the validated signature data and the first and second copies of the signature data with the validated copy of the signature data.

37. The article of manufacture of claim 36, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that matches the first and second copies of the signature data or validating one storage device signature data that has a generation number one greater than the generation number of the matching first and second copies of the signature data and where the one storage device signature data and the first and second copies of the signature data identify a common storage device.

38. The article of manufacture of claim 36, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that has a generation number equal to or one greater than a largest generation number of the first and second copies of the signature data in response to determining that the generation numbers of the first and second copies of the signature data do not match and that the first and second copies of the signature data identify the validated storage device.

39. The article of manufacture of claim 27, wherein determining the validity of one copy of the signature data comprises validating one storage device signature data that has a generation number greater by one or equal to the generation number in one of the first and second copies of the signature data in response to determining that signature data in the storage devices identifies the storage devices.