I was busy setup the demo solution for the Cisco summit yesterday. The Demo we had were displaying the VMware, Cisco UCS, Nexus 5000, MDS 9124 & Netapp Storage Solution. 1 of the Surprise thing happened during the setup, which the power source for our MDS 9124 had been tripped during the installation yesterday. In this scenerio, all our connection to ESX host and VM were disconnected. It took us for 25 mins to recovered the power failure and the MDS Switch was back on line after that. I was thought to reboot all the ESX host as we are performing BOOT FROM SAN for all the ESX hosts that we setup. Surprise happened here, which I found all the ESX host were still continue running. I did the command uptime and check the system uptime from vcenter, it showed that the ESX host were not rebooted during the SAN connection drop from UCS to our Netapp FAS storage.

I further checked the virtual machines been power on in the ESX servers, which show all the VM were continue running without system crash or rebooted. Now I realize that the failure on SAN switch may not necessary result system crash or hung, in fact it may allow you resume the system state once the SAN switch are back online, of course, this is no guarantee assumption, just some surprise finding experienced yesterday would like to share here.