VSphere High Availability explained: Monitor VMs and applications

VMware vSphere High Availability is a utility that restarts failed VMs on alternative host servers to reduce downtime for critical applications. With vSphere HA, you can pool physical servers on the same network into a high availability cluster. HA can then detect VM failures and outages and restart them on other stable systems in the cluster in the event of a problem. HA automates VM failover and helps organizations improve availability. Using the Fault Domain Manager agent, it monitors ESXi host availability via a host's "heartbeat" -- a signal VMware Tools generates to monitor availability. You can define affinity and anti-affinity rules in HA to ensure VMs remain where they belong.