I noticed that one of the servers I had set up recently was saved and then restored by Hyper-V without anyone having requested such an action.
I checked the event log and saw the following error in the Hyper-V-Hypervisor log:
Hyper-V failed creating a new partition (Status "11").
What is that error message trying to tell me and what kind of partitions is Hyper-V creating at runtime?
At this time, I'm not sure if the error is logged before or after the machine restart or if there is even any relation between the two events. But this identical error has been logged multiple times in the recent past. The new server isn't actively being used right now, so nobody would have noticed it restarting.
The guest is 2012 R2 and the host is 2008 R2