@Danp the issue is "resolved" only because we got the host back online so it released the lock. Yes I did try Start on which is method that produced the "The VDI is not available" error no the offline host was not the pool master Yes the VDI's are on shared iSCSI storage (truenas) And I want to note that OTHER VM's that were not on that failed host were able to restart and on any other node without an issue. I was even able to delete old snapshots without an issue so clearly the storage was online and available. It is deeply concerning that we were unable to get the VMs running again and only coincidental that were were able to re-seat the ram module and get it back online -- once it rejoined the pool the locked VM started without any issues on another host, so something was clearly locking it down even though it was fully stopped and visible.