I just noticed the following, when creating a new(!) HA cluster on VirtualCenter 2.5 Update 2 the default isolation response is set to “Leave powered on”. In other words, when your ESX host hasn’t got a network connection any more the VM’s remain on. This is a huge change because the default used to be “Power Off”.
Besides “Power Off” and “Leave powered on” there’s a new option introduced. And this is one I was looking for, “Shutdown VM”. Shutdown VM doesn’t just pull the cord, it tries to shutdown the VM in a decent fashion, via the OS.
I think this is a good change because if you are in an environment where there is a risk that a junior network guy mess something up, you can end up with spanning tree problems for a few minutes. In that case you do not want _all_ ESX hosts to think they are isolated and _all_ VMs shut down. It’s better that they are left powered on till the network is stable again.
I think it outweights the other option where a single ESX actually becomes network isolated but keeps looks on the files so no other ESX can take over the VMs on that specific ESX. The probability for this happening is quite low (that all NICs fail), I rate the spanning tree problems more likely since I’ve seen it twice, not fun with 200 VMs
On a real ESX or server crash, the file locks would be released as normal and other ESXes can take over.