Immediate Image Snapshots
At present, only one image snapshot can be active at a time. This can cause image requests to be queued, sometimes for hours. This can result in a snapshot that is not actually of the server at the time the snapshot was requested, but of a later state.
This blueprint proposes a change to how snapshots are created and queued. Instead of queuing the request, the snapshot should be taken immediately (note: still asynchronously, but immediately by the server). The transmission of the snapshot file(s) to the backend image store can then be queued to take place as the schedule permits.
This may result in a different state transition plan than that specified in http://
SAVING => SENDING => ACTIVE|ERROR
(Or, the state changes may be merely internal, but I think it would be good to permit the user to know that the snapshot has been made so that he or she may continue work on the server.)
Blueprint information
- Status:
- Complete
- Approver:
- None
- Priority:
- Undefined
- Drafter:
- Glen Campbell
- Direction:
- Needs approval
- Assignee:
- None
- Definition:
- Obsolete
- Series goal:
- None
- Implementation:
-
Unknown
- Milestone target:
- None
- Started by
- Completed by
- Vish Ishaya
Related branches
Related bugs
Sprints
Whiteboard
The reasoning behind this and the use case is:
1. User builds a new VPS
2. Sets up a tonne of stuff on it and it looks good
3. They want to take a snapshot so that, if the next thing they do screws things up .. they can get back to a working system
Another use case .. is where the VPS owner needs to try something dangerous such as an inplace linux distro upgrade. You'd want a snapshot before you start so you can go back if something bad happens.
Old way:
Hit snapshot .. wait 3 hours while it's queued and find some other work to do.
or worse .. believe that hitting snapshot is instant .. and immediately proceed to screw up your VPS.
New way:
Hit snapshot .. wait a few moments for it to run. Continue with your work.
hi,Campbell
I agree with you,my suggestion is when make a snapshot ,nova api just create a copy of the current instance disk file ,which has a backing file in _base directory.because the disk is very small compare to the actial image.also ,it takes less time to upload the copy to glance .
