Online / Live Migration with ZFS-Replicated local VMs?

[n1nj4888]

Hi There,

Is there a technical reason why Online / Live Migration of VMs that are replicated across local disks (from Node 1 local-zfs to Node 2 local-zfs) does not currently seem to be permitted? If this is not currently permitted / available, is it planned to be made available in Proxmox 6 Final or the future?

My understanding is that ZFS replication of VMs is there to enable a quick spin up a replicated VM on Node 2 should Node 1 go down (via HA only currently?) ... but Online / Live Migration of replicated VM to Node 2 would also be great in case of planned work on Node 1... In this case, presumably the Online / Live Migration should just replicate the delta since last scheduled replication and move the VM to Node 2?

Thanks!

 

[dcsapak]

the technical reason is that to live migrate with a local disk, we have to do a qemu drive-mirror to an nbd server on the target
this does not work currently with a snapshot as base afaik and definitely cannot use a zfs send/receive instead
what could work (but no one works on this currently) is some kind of 'pause vm; replicate; live migrate in paused state; start on the target' but this would have some down time depending on the delta/network/etc.

what works already is to shutdown, offline migrate (only the delta will be sent), and start on the target node

 

[n1nj4888]

Thanks for the detailed response!

what could work (but no one works on this currently) is some kind of 'pause vm; replicate; live migrate in paused state; start on the target' but this would have some down time depending on the delta/network/etc.

This sounds like a good alternative. If this is not being worked on currently, should I raise it as a bug/feature request through bugzilla?

Thanks!

 

[dcsapak]

should I raise it as a bug/feature request through bugzilla?

yes you can of course but no promises when or if this will get implemented

 

[tom]

https://bugzilla.proxmox.com/show_bug.cgi?id=2286

 

[mailinglists]

@dcsapak
there is also an option to "cheat" with this implementation and migrate suspended VMs.
In this case, all you need to fix is locking mechanism. See here: https://bugzilla.proxmox.com/show_bug.cgi?id=2252
As a bonus, we also get to keep ZFS snapshots on migration!