Explanation: http://docs.oracle.com/cd/E11081_01/doc/doc.21/e10898/ha.htm
To enable HA, you must first make sure all Virtual Machine Servers in the server pool:
Use the same shared storage.
Are in the same OCFS2 or NFS cluster.
Are Oracle VM Server Release 2.1.2 or above.
Have the same cluster root, which is a specially designated shared storage used for heatbeating in the cluster. For example, the cluster root might be example.com:/OVS for an NFS cluster, or /dev/sdd6 for an OCFS2 cluster. The heartbeat file would be located at example.com:/OVS/.server_pool_hb for an NFS cluster. There is no heartbeat file for an OCFS2 cluster as one is in-built in the file system.
Have the cluster root mounted at /OVS. All other storage may be mounted at the standard location of /OVS/uuid.
Have moved any /OVS mount points (set in FSTAB for Releases 2.1 or 2.1.1) to the /etc/ovs/repositories file. All storage, even that mounted at /OVS, must be maintained in the /etc/ovs/repositories file. You can move the mount points to the /etc/ovs/repositories file with the following command:
# /usr/lib/ovs/ovs-cluster-check --alter-fstab
Have a shared cluster root at /OVS, and not local, using clustered OCFS2 on SAN, or ISCSI storage, or NFS on NAS. The default local storage is OCFS2, and is notsupported with HA.
