Server 2012 R2 on beefy PowerEdge R720 dual cluster
CAU worked fine on my cluster long time ago when there was few simple VMs.
As the setup got a big more complicated (more VMs with more disks, more backend iSCSI storage, some VMs in cluster setup), CAU just does not work reliable at all.
So this time I was doing hosts WU by hand (migrated VMs to Host A, updated Host B, restarted, updated again as some updated failed, restarted fresh again, Resume/Do not fail back roles (to be on the safe side...)
Then I selected some running VMs on Host A & Live Migration them back to Host B... at which point Host B (one just updated & freshly rebooted) thrown a fit & killed all VMs that were selected to be moved to it...
"The cluster Resource Hosting Subsystem (RHS) process was terminated and will be restarted. This is typically associated with cluster health detection and recovery of a resource. Refer to the System event log to determine which resource and resource DLL is causing the issue."
Cluster service did restart & did bring the machines up, but that is less then user friendly, had to select them one more time to migrate (and this time they did)
But the whole solution just feels not like Enterprise product (in fact it would not be acceptable even for home use)
Do not expect any miracle solution, but if anybody has any experience to chip in, it would be appreciated
Seb