VMware: Real difference between VMware HA 4.x & vSphere 5.x
Capability VMware HA 4.x vSphere HA 5.x Agents VMware HA in vSphere 4.x has AAM (Automated Availability Manager) agents VMware HA in vSphere 5.x has FDM (Fault Domain Manager) agents installed Cluster Members The first five hosts added to the cluster are designated as primary hosts, and all subsequent hosts are designated as secondary hosts. If a primary host is removed from the cluster, VMware HA promotes another (secondary) host to primary status. Each host in the cluster functions as a master host or a slave host. Only one master host exists per cluster and all other hosts are slave hosts. If the master host fails, is shut down, or is removed from the cluster a new election is held. Responsibilities Primary Hosts: Decide where to restart virtual machines. Keep track of failed restart attempts. Determine when it is appropriate to keep trying to restart a virtual machine Master Host: Monitors the state of slave hosts. If a slave host fails or