vm stuck on backup

[toto-ets]

I started a backup of a vm that reached 100% and it wouldn't go any further, I aborted the backup, but now the vm remains with the lock and if I try to delete the uncompleted backup it gives me this error,
TASK ERROR: proxmox-backup-client failed: Error: unable to acquire lock on snapshot directory "/mnt/datastore/Datastore_BPS/vm/123/2025-01-19T11:16:15Z" - possibly running or in use, what should I do to unlock the vm and try the backup again?

 

[UdoB]

qm unlock <vmid> may be what you are looking for...

 

[toto-ets]

ok, this worked, but I wanted to understand why it got stuck at 100%, and wouldn't go forward, now I'll try to redo the bkp, let's see what happens

 

[UdoB]

ok, this worked,

Fine

but I wanted to understand why it got stuck

I have no idea, so this is no solution but just brainstorming:

1) search for "fleece" / "fleecing" in the backup context
2) make sure to have free space in /var/tmp
3) disable all write caches
4) watch "IO delay" during backup, on both the source and the destination - and check if it stays high (whatever that means) after the formal end of the backup