During the creation of a vSphere HA cluster, the FDM agent is deployed on each ESXi host. In addition, one host is elected as the master and all other hosts are assigned as slaves. The role of the master host is to continuously monitor the state of the slave hosts and detect issues within the cluster. The master also holds the list of virtual machines that are currently being protected by vSphere HA and is responsible for the replacement and restarting of those virtual machines should a vSphere HA event occur. If the master host fails, becomes isolated, partitioned, or disconnected from vCenter Server, it is placed into maintenance mode, has its vSphere HA agent reconfigured, or is rebooted, and another host is elected as master.