System and method for storage of snapshot metadata in a remote file

• US 20060112151A1
• Filed: 01/09/2006
• Published: 05/25/2006
• Est. Priority Date: 03/19/2002
• Status: Active Grant

• Current Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Manley, Stephen L., Edwards, John K., Chen, Raymond C.
• Granted Patent: US 7,644,109 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/184 implemented as replicated file system
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

A system and method for conforming a metadata file associated with qtree of a storage system to a version used by a file system kernel of the storage system, where the version indicates a format of the metadata file. The metadata file stores state information with respect to each qtree, and may be located outside of the qtree structure. Major and minor versions are compared with latest known major and minor versions associated with the file system kernel. In response to such comparisons, the metadata file may be updated to a newer version, rolled back to an older version, and/or the system may enter a corrective state where further operations are performed.

Claims

1. A method for conforming a metadata file associated with a sub-organization of a storage system to a version used by a file system kernel of the storage system, where the version indicates a format of the metadata file, the method comprising the steps of:

comparing a major version and a minor version of the metadata file to a latest known major version and a latest known minor version associated with the file system kernel;

if either the major version or the minor version of the metadata file are older than the latest known major version and a latest known minor version, updating the metadata file to the latest known major version and the latest known minor version; and

if the major version of the file matches the latest known major version, and the minor version of the metadata file is newer than the latest known minor version, converting one or more fields of the metatdata file that are not recognized by the kernel to a non-informational state, and resetting the minor version of the metadata file to the latest known minor version.

2. The method as set forth in claim 1 further comprising the step of:

if the major version of the metadata file is newer than the latest known major version, entering a corrective state.

3. The method as set forth in claim 2 wherein the step of entering the corrective state comprises a halt by the kernel in processing the metadata file.

4. The method as set forth in claim 1 wherein the sub-organization is a sub-organization of a volume on the storage system.

5. The method as set forth in claim 1 wherein the sub-organization comprises a qtree and the metadata file is a qtree metatdata file.

6. The method as set forth in claim 5 wherein at least one of the fields of the metatdata file includes a qtree identifier.

7. The method as set forth in claim 5 wherein the qtree metadata file is located outside of the qtree and the metadata file is a qtree metatdata file.

8. The method as set forth in claim 1 wherein the metadata file includes a plurality of fixed length records each including a plurality of fields storing state information.

9. The method as set forth in claim 8 wherein information defining the major version and the minor version is stored in a header record associated with one or more of the fixed length records.

10. The method as set forth in claim 8 wherein each of the plurality of fixed length records includes a latest exported snapshot ID.

11. The method as set forth in claim 1 wherein the step of converting one or more fields not recognized includes associating the fields not recognized with a spare space having a zeroed value.

12. A method for recording changes to a metadata file associated with a sub-organization of a storage system to conform to a version used by a file system kernel of the storage system, the method comprising the steps of:

storing one or more changes to the metadata file in a non-volatile memory of a file server adapted to retain the changes upon unintended shutdown; and

if an unintended shutdown occurs, replaying changes logged in the non-volatile memory and updating the metadata file with the changes.

13. A system for conforming a metadata file associated with a sub-organization of a storage system to a version used by a file system kernel of the storage system, where the version indicates a format of the metadata file, the system comprising:

means for comparing a major version and a minor version of the metadata file to a latest known major version and a latest known minor version associated with the file system kernel;

means for updating the metadata file to the latest known major version and the latest known minor version if either the major version or the minor version of the metadata file are older than the latest known major version and a latest known minor version; and

means for converting one or more fields of the metadata file that are not recognized by the kernel to a non-informational state, and resetting the minor version of the metadata file to the latest known minor version, if the major version of the file matches the latest known major version, and the minor version of the metadata file is newer than the latest known minor version.

14. The system of claim 13 further comprising:

means for entering a corrective state. if the major version of the metadata file is newer than the latest known major version.

15. The system of claim 14 further comprising:

means for halting processing of the metadata file while in the corrective state.

16. The system of claim 13 wherein the sub-organization is a sub-organization of a volume on the storage system.

17. The system of claim 13 wherein the sub-organization comprises a qtree and the metadata file is a qtree metatdata file.

18. The system of claim 17 wherein at least one of the fields of the metatdata file includes a qtree identifier.

19. The system of claim 17 wherein the qtree metadata file is located outside of the qtree and the metadata file is a qtree metatdata file.

20. The system of claim 13 wherein the metadata file includes a plurality of fixed length records each including a plurality of fields storing state information.

21. The system of claim 20 wherein information defining the major version and the minor version in stored in a header record associated with one or more of the fixed length records.

22. The system of claim 20 wherein each of the plurality of fixed length records includes a latest exported snapshot ID.

23. The system of claim 20 wherein the means for converting further comprises:

means for associating one or more fields not recognized with a spare space having a zeroed value.

24. A system for recording changes to a metadata file associated with a sub-organization of a storage system to conform to a version used by a file system kernel of the storage system, the system comprising:

means for storing one or more changes to the metadata file in a non-volatile memory of a file server adapted to retain the changes upon unintended shutdown; and

means for replaying changes logged in the non-volatile memory and updating the metadata file with the changes if an unintended shutdown occurs.

25. A computer readable medium containing executable program instructions for conforming a metadata file associated with a sub-organization of a storage system to a version used by a file system kernel of the storage system, the executable program instructions comprising program instructions for:

comparing a major version and a minor version of the metadata file to a latest known major version and a latest known minor version associated with the file system kernel;

if either the major version or the minor version of the metadata file are older than latest known major version and a latest known minor version, updating the metadata file to the latest known major version and the latest known minor version; and

if the major version of the file matches the latest known major version, and the minor version of the metadata file is newer than the latest known minor version, converting one or more fields of the metatdata file that are not recognized by the kernel to a non-informational state and resetting the minor version of the file to the latest known minor version.

26. A computer readable medium containing executable program instructions for recording changes to a metadata file associated with a sub-organization of a storage system, the executable program instructions comprising program instructions for:

storing one or more changes to the metadata file in a non-volatile memory of a file server adapted to retain the changes upon unintended shutdown; and

if an unintended shutdown occurs, replaying changes logged in the non-volatile memory and updating the metadata file with the changes.

27. A method for using a metadata file by a file system kernel, the method comprising the steps of:

reading a field of the metadata file to determine a metadata file'"'"'s major version and a metadata file'"'"'s minor version;

modifying the metadata file by

a) if either the metadata file'"'"'s major version or the metadata file'"'"'s minor version are older than a file system kernel'"'"'s major version and a file system kernel'"'"'s minor version, updating the metadata file and assigning the metadata file the same major version and minor version as the file system kernel, or

b) if the metadata file'"'"'s major version matches the file system kernel'"'"'s major version, and the metadata file'"'"'s minor version is newer than the file system kernel'"'"'s minor version, ignoring one or more fields of the metatdata file that are not recognized by the file system kernel, and changing the metadata file'"'"'s minor version to be the same as the file system kernel'"'"'s minor version.

28. The method as set forth in claim 27 further comprising the step of:

halting processing of the metadata file if the metadata file'"'"'s major version is newer than the file system kernel'"'"'s major version.

29. The method as set forth in claim 27 wherein the metadata file describes a qtree of a volume.

31. A system for using a metadata file, the system comprising:

means for reading a field of the metadata file to determine a metadata file'"'"'s major version and a metadata file'"'"'s minor version;

means for modifying the metadata file such that

a) if either the metadata file'"'"'s major version or the metadata file'"'"'s minor version are older than a file system kernel'"'"'s major version and a file system kernel'"'"'s minor version, the metadata file is updated and assigned the same major version and minor version as the file system kernel, or

b) if the metadata file'"'"'s major version matches the file system kernel'"'"'s major version, and the metadata file'"'"'s minor version is newer than the file system kernel'"'"'s minor version, one or more fields of the metadata file that are not recognized by the file system kernel are ignored and the metadata file'"'"'s minor version is changed to be the same as the file system kernel'"'"'s minor version.

32. The system as set forth in claim 31 further comprising:

means for halting processing of the metadata file if the metadata file'"'"'s major version is newer than the file system kernel'"'"'s major version.

33. The system as set forth in claim 31 wherein the metadata file describes a qtree of a volume.