Nothing will make a Hyper-V admin bald faster than storage issues. Whether it’s ODX on HP 3par or networking issues caused by Emulex, even if the blip is transient, it will crash your VMs. This all changes in vNext.
The next version of Hyper-V is more tolerant of storage issues. A VM will enter a paused state when the hypervisor detects an underlying storage issue. This will protect the VM from an unnecessary stoppage in the case of a transient issue. If the storage goes offline just for a few seconds, then the VM goes into a pause state for a few seconds, and there’s no stoppages, reboots, or database repairs.
We have still some old ESX 3.5 Cluster running that sometimes looses whole connectivity to the fibre san for about 2 minutes!!! However the VMs continue to run and just log “disk”-event errors until they can connect to the storage again. I was under the impression that Hyper-V in its current state can survive the same. Do no get me wrong. I am Hyper-V fan, but did not really expect that this is an issue…
Our Hyper-V Cluster survived 5 out of 6 nodes losing connectivity to the SAN and the remaining host losing one of two connections thanks to CSV redirection. I guess this is just one more thing to improve high availabilty.