[Users] Automated Failover

Hello, i am currently running two nodes with VMs on it. They are all set up as "High Available". However, if i unplugg a node and turn it off, the VMs wont get started on the 2nd node. Do i need fencing, watchdog or anything else to get this feature work? Since i have two nodes and one ovirt engine this should be enough for quorum. Where can read up more in detail how the heartbeat and automated failover works? Thanks, Mario