Method and apparatus for recovery of a current read-write unit of a file system

• US 20050278382A1
• Filed: 05/28/2004
• Published: 12/15/2005
• Est. Priority Date: 05/28/2004
• Status: Abandoned Application

• Current Assignee: NetApp, Inc.
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Tummala, Narayana, LaRocca, Michael J., Snider, William L.
• Application Number:
  US10/856,448
• Publication Number:
  US 20050278382A1
• 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 11/2005 using redundant communication controllers
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

An apparatus for recovering a current read-write Virtual File System (VFS) includes a network element which receives client requests and makes calls responding to the client requests. The apparatus includes a VFS location database which maintains information about VFSes. The apparatus includes a disk element in which VFSes are disposed and which, when effective access to the current read-write VFS is lost, the disk element promotes a read-only VFS of the current read-write VFS to a read-write VFS. A method for recovering a current read-write VFS includes the steps of losing effective access to the current read-write VFS. There is the step of promoting a read-only VFS of the current read-write VFS to a read-write VFS.

Claims

1. A method for recovering a current read-write unit of a file system comprising the steps of:

losing effective access to the current read-write unit; and

promoting a read-only unit of the file system of the current read-write unit to a read-write unit of the file system.

2. A method as described in claim 1 wherein the unit of the file system includes a VFS and including the step of selecting a candidate read-only VFS which is to be promoted into the current read-write VFS.

3. A method as described in claim 2 including the step of modifying meta-data for the candidate read-only VFS enabling client-requests to be serviced by the candidate read-only VFS once the candidate read-only VFS has been promoted to the read-write VFS.

4. A method as described in claim 3 wherein the selecting step includes the step of selecting by an administrator the candidate read-only VFS which is to be promoted into the current re-write the VFS.

5. A method as described in claim 4 wherein the selecting step includes the step of selecting the candidate VFS from a group of a spinshot or mirror of the current read-write VFS.

6. A method as described in claim 5 including the step of assigning a VFS ID of the current read-write VFS to the candidate read-only VFS.

7. A method as described in claim 6 including the step of deleting the current read-write VFS.

8. A method as described in claim 7 wherein the deleting step includes the step of deleting any record of the current read-write VFS from the VLDB.

9. A method as described in claim 8 including the step of setting the candidate read-only VFS'"'"'s identity to the current read-write VFS'"'"'s identity in the VLDB and on a D-blade.

10. A method as described in claim 9 wherein the setting step includes the step of changing the candidate read-only VFS'"'"'s name to the current read-write VFS'"'"'s name.

11. A method as described in claim 10 wherein the setting step includes the step of changing the candidate read-only VFS type to read-write.

12. A method as described in claim 11 including the step of forming a mirror chain from spinshots of the current read-write VFS.

13. A method as described in claim 12 wherein the candidate read-only VFS has a data version, and including the step of swapping with the candidate read-only VFS a VFS ID of a spin shot in the chain with a data version that is less than or equal to the data version of the candidate read-only VFS for a mirror whose data version is greater than the data version of the candidate read-only VFS.

14. A method as described in claim 13 including the step of deleting a VLDP record of a mirror spinshot selected for swapping its VFS ID that is inaccessible.

15. A method as described in claim 14 including the step of deleting a mirror from the D blade and setting the mirror data version in the VLDB if no mirror spinshot of the chain is found for swapping its VFS ID to insure a full copy is performed for a next mirror of the current read-write VFS.

16. A method as described in claim 15 including copying the current read-write VFS content to a storage pool when the current read-write VFS is initially mirrored.

17. A method as described in claim 16 including copying an incremental change, represented by a delta between the data versions of the current read-write VFS and the initial mirror, to a subsequent mirror of the current read-write VFS when the subsequent mirror is performed.

18. A method as described in claim 1 wherein the promoting step includes the step of restoring the current read-write VFS within one minute of losing effective access to the current read-write VFS.

19. A method as described in claim 1 wherein the promoting step is transparent to a client.

20. A method as described in claim 1 including the step of preserving the current read-write VFS family relationship to eliminate any possibility of corrupting data on a subsequent operation.

21. An apparatus for recovering a current read-write unit of a file system comprising:

a network element which receives client requests and makes calls responding to the client requests;

a unit of the file system location database which maintains information about units of the file system;

a disk element in which the units are disposed; and

a manager which, when effective access to the current read-write unit is lost, the manager promotes a read-only unit of the file system of the current read-write unit to a read-write unit of the file system, the manager in communication with the disk element.

22. An apparatus as described in claim 21 wherein the unit of the file system includes a VFS and the manager restores the current read-write VFS within one minute of losing effective access to the current read-write VFS.

23. An apparatus as described in claim 22 including a storage pool in the disk element in which content of a VFS is stored.

24. An apparatus as described in claim 23 wherein the information about a VFS in the VFS location database identifies the VFS by name, ID and storage pool ID.

25. An apparatus as described in claim 24 wherein the manager uses a candidate read-only VFS which is to be promoted into the current read-write VFS that has been selected by an administrator.

26. An apparatus as described in claim 25 wherein the manager uses the candidate VFS selected by the administrator from a group of a spinshot or mirror of the current read-write VFS.

27. An apparatus as described in claim 26 wherein the disk element includes a D-blade.

28. An apparatus as described in claim 27 wherein the network element includes an N-blade.