Optimized rollback of copy-on-write snapshot volumes
The present invention is an optimized method for the rollback of copy-on-write snapshot volumes. A method in accordance with the present invention may comprise the following steps: (a) creating a copy-on-write snapshot volume; (b) receiving a base volume write request addressed to a base volume data block; (c) executing copy-on-write operations; (d) receiving a snapshot volume rollback request; (e) disabling the copy-on-write operations; and (f) executing volume copy operations.
1. A method for snapshot volume rollback, the method comprising the steps:
creating a copy-on-write snapshot volume;
receiving a base volume write request addressed to a base volume data block;
executing copy-on-write operations;
receiving a snapshot volume rollback request;
disabling the copy-on-write operations; and
executing volume copy operations.
2. The method of claim 1 , wherein the creating a copy-on-write snapshot volume comprises:
creating a snapshot image volume comprising meta-data referencing base volume data blocks; and
creating a repository volume comprising copy-on-write data.
3. The method of claim 1 , wherein the base volume write request is received from an external host.
4. The method of claim 1 , wherein the base volume write request is received from a RAID controller.
5. The method of claim 1 , wherein the step of executing copy-on-write operations further comprises the steps:
copying a base volume data block addressed by the base volume write request to a repository volume; and
dereferencing meta-data of a snapshot image volume which references the base volume data block addressed by the base volume write request.
6. The method of claim 1 , wherein the receipt of the snapshot rollback request disables the copy-on-write operations.
7. The method of claim 1 , wherein the step of executing volume copy operations further comprises the step:
copying base volume data blocks previously copied to a repository volume via a copy-on-write operation to the base volume.
8. The method of claim 7 , wherein the step of executing volume copy operations further comprises the step:
copying base volume data blocks referenced by snapshot image volume meta-data to the base volume.
9. The method of claim 1 , wherein the snapshot volume rollback request is made by an external host.
10. The method of claim 1 , wherein the snapshot volume rollback request is made by an internal RAID controller.
11. The method of claim 1 , wherein a source volume for the volume copy operations is a snapshot volume and a target volume for the volume copy operations is a base volume.
12. A computer-readable medium having computer readable instructions stored thereon for execution by a processor to perform a method the method comprising the steps:
creating a copy-on-write snapshot volume; receiving a base volume write request addressed to a base volume data block;
executing copy-on-write operations;
receiving a snapshot volume rollback request;
disabling the copy-on-write operations; and
executing volume copy operations.
13. The computer-readable medium of claim 12 , wherein the copy-on-write snapshot volume comprises:
creating a snapshot image volume comprising meta-data referencing base volume data blocks; and
creating a repository volume.
14. The computer-readable medium of claim 12 , wherein the base volume write request is received from an external host.
15. The computer-readable medium of claim 12 , wherein the base volume write request is received from a RAID controller.
16. The computer-readable medium of claim 12 , wherein the step of executing copy-on-write operations further comprises the steps:
copying a base volume data block addressed by the base volume write request to a repository volume; and
dereferencing meta-data of a snapshot image volume which references the base volume data block addressed by the base volume write request.
17. The computer-readable medium of claim 12 , wherein the receipt of the snapshot rollback request disables the copy-on-write operations.
18. The computer-readable medium of claim 12 , wherein the step of executing volume copy operations further comprises the step:
copying base volume data blocks copied to a repository volume to the base volume.
19. The computer-readable medium of claim 18 , wherein the step of executing volume copy operations further comprises the step:
copying base volume data blocks referenced by the snapshot image volume meta-data to the base volume.
20. The computer-readable medium of claim 12 , wherein the snapshot volume rollback request is made by an external host.
21. The computer-readable medium of claim 12 , wherein the snapshot volume rollback request is made by a RAID controller.
22. The computer-readable medium of claim 12 , wherein a volume copy source is a snapshot volume and a volume copy target is a base volume.