[pve-devel] Low downtime alternative for container migration

[Teemu Grönqvist]

Hello everyone,

Proxmox requires containers to be offline during migration. It takes a 
lot of time for say LVM migration before the container will be up again, 
because Proxmox will first shutdown the container, then move the disk 
information (if disk is not shared) and after that, start the container 
on the new host.

What should be done instead: snapshot the container (if possible), 
migrate the snapshot information, remove the snapshot, shutdown the 
container, rsync the changes over from container filesystem and after 
that start the container on the new host.

This option would tremendously reduce container downtime when migrating 
over without shared storage, because we would only have to transfer 
changes that happened between taking the snapshot and finishing it's 
transfer to the other host. I've been migrating containers by hand using 
this for a while now, because of the smaller downtime benefits it gives.

Would you be interested in such feature? I could work on a patch as I 
myself have a lot of interest for this.

Kind regards,
Teemu Grönqvist
Net9 Oy