ZFS Snapshot Deletion Question

EagleTG

Active Member
Jun 18, 2020
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Hi all,

I've got a VM running on Proxmox which is connected to a FreeNAS instance. Full disclosure, I'm using GrandWazoo's plug-in (and realize that is not supported in this forum), but am unsure if it related to the issue. Hence, my question is specific to a ZFS state dataset that I am unable to delete.

A quick run-down of what I did, and what went wrong:
  • I created a snapshot of a Powered-on VM
  • I deleted said snapshot, received an error:
    "TASK ERROR: error during cfs-locked 'storage-freenasblk01' operation: Unable to delete lun /dev/zvol/freenas01/vm-106-state-Snapshot_Name"
  • The VM dropped into a locked state
  • After a bit of Googling, I removed the snapshot entry from the /etc/pve/qemu-server/106.conf file
  • I did a qm unlock 106
  • I also manually removed the snapshot from the FreeNAS / ZFS using:
    zfs destroy freenas01/vm-106-disk-0@Snapshot_Name
This seems to have cleaned up the issue, but I am still seeing a reference to the machine state in /dev/zvol/freenas01 named vm-106-state-Snapshot_Name.

I tried removing this via:
zfs destroy freenas01/vm-106-state-Snapshot_Name

But received an error that stated:
"cannot destroy 'freenas01/vm-106-state-Snapshot_Name': dataset is busy"

I'm guessing this was the initial issue with deleting the snapshot via the UI.

I've since been able to create a new snapshot and everything is working as-expected. The errant "vm-106-state-Snapshot_Name" still exists. Does anyone know how I can remove this file? I have not tried rebooting any of the hosts, but have tried migrating the VM to another host (a trick that sometimes worked with VMware storage weirdness) to no avail.

The leftover "state" datastore doesn't seem to be hurting anything, but I'd like to clean it up if possible.
Any thoughts?
Thanks all!!