I recently started working at a location that uses Proxmox 3.x with kernel Linux ilsbnode2 2.6.32-48-pve #1 SMP Fri Nov 25 06:28:35 CET 2016 x86_64 GNU/Linux. There are several openVZ containers. There is just one node. There is a ZFS filesystem. Since the system was built, the ZFS file system had grown to petabytes. Things I noticed. No multi node cluster. Single point of failure, local storage and no backups. I was going to start planning a redesign with a four node HA cluster after some study. The node rebooted unexpectingly on 12/19/2016. As a result, the ZFS file system failed to mount. The openVZ containers would not start because ZFS file systems failed to mount. The conclusion was to plan an upgrade to version 4 and preserve the ZFS data. I was able to ssh in remotely to the node and run the GUI and see the containers. Once I came back to the server room, I found that the pve services are not running and I cannot find the ZFS data.