After configuring HA for a vSphere 5 cluster, you may encounter the following warning on each ESX host:

Configuration Issues
The number of vSphere HA heartbeat datastores for this host is 1, which is less than required: 2

vSphere 5 introduces datastore heartbeats in addition to network hearts, which allows to distinguish between a network-isolated host and a crashed host. In order for datastore heartbeats to work properly, vSphere requires at least 2 shared datastores available on every host in the cluster. If there's less than 2 shared datastores, datastore heartbeats will not function properly, resulting in the configuration issue message.

If you only have one shared datastore and wish   ...