Support snapshot active/inactive
Let Cinder support to create inactive snapshot and then give users a choice to decide when will they active the inactive snapshot.
Blueprint information
- Status:
- Not started
- Approver:
- None
- Priority:
- Undefined
- Drafter:
- wangxiyuan
- Direction:
- Needs approval
- Assignee:
- wangxiyuan
- Definition:
- Discussion
- Series goal:
- None
- Implementation:
-
Unknown
- Milestone target:
- None
- Started by
- Completed by
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Hey Wangxian, can you explain a little more what you mean by inactive snapshot?
Re:
Actually this is a private feature in our production. After some discussion and investigation, I think that it's a not a common feature for Cinder. So I'll abandon this BP. (Or some other third part storage support this as well? I don't really know. At least, LVM and Ceph don't AFAIK)
For anyone who is interested in the inactive/active snapshot. I'd like to say more here: As we know, most drivers use COW(copy on write) for volume's snapshot. A snapshot mapping table(or whatever else) will be created at the storage backend once the snapshot's creataion request is sent to the driver. So In the vm full-backup use case, we need the vm's device should be snapshoted at the same time so that to keep the data consistence. But now in Nova, it create the snapshot for the vm's volumes one by one which means that the data is not in a consistence. So In our prodution, we firstly create some inactive snapshot. Then active them at the same time once they are all ready.
I don't know what's the difference between inactive and active snapshot in the storage backend. Perhaps for the inactive snapshot, the mapping table is already exist but the timestamp are not?
