I have two Windows 2012 R2 servers. Let's call them SourceBox and ReplicaBox. There are 2 VMs running and they were replicating perfectly. Let's call them VM1 and VM2.
I had a problem with my APC UPS on the SourceBox and it rebooted during the UPS self-test. When the SourceBox came back up, the VMs started and appear to be working fine.
HOWEVER, the replication Health read "Critical - Resynchronization Required". I attempt to do that and even though it appears to resynchronize, the health is left with a state of critical and it wants me to resynchronize again.
I've found the ONLY way to fix this is to remove the replication, delete the VM from the ReplicaBox, then recreate the replica from scratch which re-initates a seed copy.
This is what I did for one of the two VMs and it worked 100% fine.
I've left the other VM in this weird state so I can troubleshoot. Upon looking at the Hyper-V event logs on the ReplicaBox, I see a few event ID's with associated messages. They are as follows:
Event ID 16370
'ReplicaBox' cannot create the the storage required for the checkpoint using disk C:\VMs\Hyper-V Replica\Virtual Hard Disks\97A58FDF-B397-48587-BB76-65D0EEC9875F\VM2.VHD
Checkpoint operation for 'VM2' failed (Virtual machine ID 97A58FDF-B397-48587-BB76-65D0EEC9875F)
Replication operation for virtual machine 'VM2' failed: General access denied error (0x80070005).
Hyper-V failed to start recynchronization for virtual machine 'VM2: General access denied error (0x80070005).
The only thing I did on the ReplicaBox when I noticed the SourceBox rebooted was immediately go into the Hyper-V settings and pause replication on VM1 and VM2.
When everything came backup, I went to ReplicaBox and selected 'Resume Replication'. However, that has had no effect.
I believe that some permissions have changed on the 'ReplicaBox' or the VHD file is in a locked state from the unexpected reboot of the source - perhaps it was in the middle of replicating changes when SourceBox rebooted.
Overall, I'd like to get the VM2 replica on ReplicaBox to resyncrhonize without having to recreate the replica and re-seed as it is a lot of data and the VHD files are already present on ReplicaBox. Just a bit out of date now - an hour or so.