@hitechhillbilly I'd say this is normal if you are low on RAM and you are doing a live VDI migration. XCP-ng requires some amount of free RAM on the host to be able to live migrate the VDI. The larger the VDI, the more RAM is needed but exact sizing is unknown to me. I've encountered this error numerous times so I consider it common.
The way around this is to shutdown the VM and then migrate the VDI. RAM requirements in that case are much much lower.
@vaewyn There is an emergency transition to new master xe command. Also, make sure all your hosts are properly time syncronized to each other or there can be pool issues.
Try first:
xe pool-designate-new-master host-uuid=<new-master-uuid>
If that fails, you will need to run on the slave server:
xe pool-emergency-transition-to-master
