Well I had a weird thing happen today and I am not entirely sure why but I wanted to describe the issue and what I did to fix it in case anyone else is googling around for it.
I recently applied some pool patches to my main xcp-ng server at a client and everything seemed to be fine. A host reboot was requested but I had planned to do that during a maintenance window.
At some point last night due to Unattended Updates a reboot of an ubuntu dns server occurred. However, it never came back up. Trying to start it from xen orchestra resulted in the error:
“FAILED_TO_START_EMULATOR(OpaqueRef:XXX-XX-XX-XXX, domid XXX, QMP failure at File “xc/device.ml”, line 3328, characters 71-78)”
Cloning a snapshot resulted in the same error. Trying to spin up a new Ubuntu 20.04 VM showed the same error. Windows VMs seemed unaffected and rebooted ok. A second Ubuntu VM that was still running ok but failed to come back up after a manual reboot.
After verifying backups of specific data I prepared to spend a long night rebuilding a VM stack but after trying to restart the toolstack on the host, everything started working again. I have since rebooted the host with no further ill effects.
Just wanted to have this info out there in case it happens to anyone else.
