System and method for updating a copy-on-write snapshot based on a dirty region log
View Patent ↗Various methods and systems for updating a copy-on-write snapshot based on a dirty region log are disclosed. For example, a method involves maintaining a dirty region log and updating a copy-on-write snapshot change tracking map, based on information in the dirty region log. In some embodiments, the copy-on-write snapshot change tracking map is updated in response to an indication of a dirty region log cleaning cycle. The dirty region log cleaning cycle is inhibited until after the copy-on-write snapshot change tracking map has been updated. The method can be used to update multiple copy-on-write snapshot change tracking maps, each of which is associated with a respective one of several copy-on-write snapshots, based on information in the dirty region log. Such a method can be performed by a virtualizing network device.
1. A method comprising:
accessing information in a dirty region log;
updating a copy-on-write snapshot change tracking map, based on the information in the dirty region log, wherein the updating is performed in response to an indication of a dirty region log cleaning cycle; and
inhibiting the dirty region log cleaning cycle until after the copy-on-write snapshot change tracking map has been updated based on the information in the dirty region log.
2. The method of claim 1 , wherein
the accessing and the updating are performed by a virtualizing network device.
3. The method of claim 2 , further comprising:
updating a plurality of copy-on-write snapshot change tracking maps, based on the information in the dirty region log, wherein
each of the copy-on-write snapshot change tracking maps is associated with a respective one of a plurality of copy-on-write snapshots.
4. The method of claim 3 , wherein
the updating is performed subsequent to completion of a write operation to a volume, and
the method further comprises updating the dirty region log in response to the write operation.
5. The method of claim 4 , further comprising:
copying a value of a region to a copy-on-write snapshot, in response to the write operation; and
performing the write operation to the region, subsequent to the copying, wherein the region stores a new value subsequent to the performing.
6. A network device comprising:
an I/O module;
a control module;
a dirty region log update module configured to maintain a dirty region log, wherein the I/O module comprises the dirty region log module; and
a change tracking map update module coupled to the dirty region log update module, wherein
the change tracking map update module is configured to update a copy-on-write snapshot change tracking map, based on information in the dirty region log, in response to receiving notification of a dirty region log cleaning cycle.
7. The network device of claim 6 , wherein the control module comprises the change tracking map update module.
8. The network device of claim 6 , wherein
the change tracking map update module is configured to inhibit the dirty region log cleaning cycle until after the copy-on-write snapshot change tracking map has been updated based on the information in the dirty region log.
9. The network device of claim 8 , wherein
the change tracking map update module is configured to update a plurality of copy-on-write snapshot change tracking maps, based on the information in the dirty region log, wherein
each of the copy-on-write snapshot change tracking maps is associated with a respective one of a plurality of copy-on-write snapshots.
10. A computer readable storage medium comprising program instructions executable to:
access information in a dirty region log;
update a copy-on-write snapshot change tracking map, based on the information in the dirty region log, in response to an indication of a dirty region log cleaning cycle; and
inhibit the dirty region log cleaning cycle until after the copy-on-write snapshot change tracking map has been updated.
11. The computer readable storage medium of claim 10 , wherein the program instructions are executable to update a plurality of copy-on-write snapshot change tracking maps, based on the information in the dirty region log, wherein
each of the copy-on-write snapshot change tracking maps is associated with a respective one of a plurality of copy-on-write snapshots.
12. The computer readable storage medium of claim 10 , wherein
the program instructions are executable to update the copy-on-write snapshot change tracking map subsequent to completion of a write operation to a volume, and
the program instructions are executable to update the dirty region log in response to the write operation.
13. The computer readable storage medium of claim 12 , wherein the program instructions are further executable to:
copy a value of a region to a copy-on-write snapshot, in response to the write operation; and
perform the write operation to the region, subsequent to the copying, wherein the region stores a new value subsequent to the performing.
14. A system comprising:
a processor; and
a memory coupled to the processor and configured to store program instructions executable by the processor to:
access information in a dirty region log;
update a copy-on-write snapshot change tracking map, based on the information in the dirty region log, in response to an indication of a dirty region log cleaning cycle; and
inhibit the dirty region log cleaning cycle until after the copy-on-write snapshot change tracking map has been updated.
15. The system of claim 14 , wherein the program instructions are executable to update a plurality of copy-on-write snapshot change tracking maps, based on the information in the dirty region log, wherein
each of the copy-on-write snapshot change tracking maps is associated with a respective one of a plurality of copy-on-write snapshots.