When you run Oracle VM with multipathing in a clustered host environment, you need to configure the O2CB_HEARTBEAT_THRESHOLD to 65.
This timeout value works with the I/O layer and sets the maximum amount of time in seconds that a node waits for an I/O operation. In the heartbeat system file, the node writes to the block every two seconds. The block offset is equal to its global node number. This means that node 0 writes to the first block, node 1 to the second block, and so on. All the nodes also read the heartbeat sysfile every two seconds. As long as the timestamp keeps changing, that node is considered "alive."