We have 6 * ESXi 5.1 with configured HA and DRS and a Vcenter 5.1.
If we put a ESXi in maintenance mode via the Vcenter gui all VMs will be migrate to the other hosts, there is no problem at all.
But if we put the the same host via VMA in maintenance mode, the VMs will go in suspend mode and the host goes in maintenance mode. On the GUI in Vcenter we get a message says that a migration will not work in the current state. Due to the fact that the message is in german it makes not so much sence to post it here, I guess.
Background is, we have two time three hosts in diffrent locations. Both locations in seperate buildings, therefor with seperate power and seperate UDP.
So if one location powerd down the udp should shut down the hosts in that location and the VMs should migrate over.
SVMotion is not necessary, the SAN is an automatc mirroring unit.
