Description of problem: Live snapshot with memory always pausing the VM while making it. Since in 4.4 we moved to async snapshot, we can prevent the VM pause in the cost of longer convergence and a bigger snapshot disk. Steps to Reproduce: 1. Create a VM. 2. Run the VM. 3. Create snapshot with memory. Actual results: VM is paused during the operation. Expected results: VM won't be paused during the operation. Additional info: This require us to use VIR_DOMAIN_SNAPSHOT_CREATE_LIVE flag when calling from VDSM to libvirt.
That's something that was discussed back in oVirt 3.3 when memory snapshots were introduced [1]. Besides the above-mentioned downsides of doing it "live", we've realized it would probably make sense to leverage the existing mechanism in VDSM for live-migration - and that was (is?) fairly complex. [1] https://www.youtube.com/watch?v=xIhPV66uGo8 24:13-25:15 :)
We are past 4.5.0 feature freeze, please re-target.
no updates for a long time, missed 4.5 GA, closing
This can be an interesting technical challenge but as this option has several downsides to this approach: 1. The snapshot operation could then fail because the 'migration' may not converge 2. The snapshot operation can take significantly more time and during this time the VM is locked exclusively 3. The volume that stores the memory dump can be significantly larger, consuming more space on the storage device 4. It would be hard to predict the size of the volume used for the memory dump so storing it on block devices would be complex So with no request for this from the field, it has never been prioritized