The absurdity of migrating a VM vs. restoring a VM from backup


Sep 5, 2020
I have a few nodes.

I have a Domain controller on one node using 15GB storage space in a 220G RAW file where more than 90% is empty.
I attempt to migrate this to a different node... 3 hours later, still not done. I stop the process as my patience ran out.

I decide to Migrate it the fast way:
-Backup DC with PBS. 10 minuttes later.. done
-Detach drives from the VM and delete the disks. 30 seconds.. done
-Migrate the VM without disks (as I just deleted them) 30 seconds.. done
-Restore the VM from PBS 10 minuttes later.. done.

Why does it take 20 minuttes to do it the fast way, but 3 hours+(an unknown amount of time) to migrate the 15GB used space using the UI?

This does not make sense!
Last edited:
I can't replicate your results. I have a 3 node cluster. Migration network is on a 10gig network with a small microtik switch. Moving a node with a single disk of 108G takes about 4.5 minutes.
you haven't given details about what kind of storage you are using on either end, but it's likely some combination that needs to fully initialize/transfer the disk including empty blocks.. PBS and VMA backups will optimize that away.
is an offline migration faster? can you post a task log?


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