Snapshot causes lock of container, failure next day

[Clete2]

I've observed this behavior twice now in the past couple of weeks. I have daily snapshot backups enabled. One particular CT, 114, ends up being locked, and then daily backups subsequently fail the next day.

Here is the log from T-1 days:

INFO: filesystem type on dumpdir is 'zfs' -using /var/tmp/vzdumptmp2075888_114 for temporary files
INFO: Starting Backup of VM 114 (lxc)
INFO: Backup started at 2024-12-13 04:10:19
INFO: status = running
INFO: CT Name: mysql
INFO: including mount point rootfs ('/') in backup
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: create storage snapshot 'vzdump'
INFO: creating vzdump archive '/tank/backup/dump/vzdump-lxc-114-2024_12_13-04_10_19.tar'
INFO: Total bytes written: 5966991360 (5.6GiB, 76MiB/s)
INFO: archive file size: 5.56GB
INFO: prune older backups with retention: keep-daily=30, keep-last=1, keep-monthly=12, keep-weekly=8, keep-yearly=1
INFO: pruned 0 backup(s)
INFO: cleanup temporary 'vzdump' snapshot
snapshot 'vzdump' was not (fully) removed - zfs error: cannot destroy snapshot rpool/data/subvol-114-disk-0@vzdump: dataset is busy
INFO: Finished Backup of VM 114 (00:01:17)
INFO: Backup finished at 2024-12-13 04:11:36

Then here is the log from the next day (today):

INFO: Starting Backup of VM 114 (lxc)
INFO: Backup started at 2024-12-14 04:11:43
INFO: status = running
ERROR: Backup of VM 114 failed - CT is locked (snapshot-delete)
INFO: Failed at 2024-12-14 04:11:43

I have to manually unlock the VM and delete the snapshot (@vzdump) in order to get tomorrow's backup to work properly. What can be done here?

 

[Clete2]

Actually, I wonder if Sanoid/Syncoid are interfering. I'm not really sure why I am doing vzdump as well as taking ZFS snapshots of those volumes. Maybe I should just turn off Proxmox's backup?

 

[leesteken]

snapshot 'vzdump' was not (fully) removed - zfs error: cannot destroy snapshot rpool/data/subvol-114-disk-0@vzdump: dataset is busy

I'm not really sure why I am doing vzdump as well as taking ZFS snapshots of those volumes.

Maybe the clean up of the backup fails because you are taking snapshots at that same time?

Maybe I should just turn off Proxmox's backup?

Snapshots are not a defense against hardware failures or fires. But it might be that your various backup tools are interfering with each other. Use what you think is best.