What Does VMware High Availability Mean?
VMware High Availability is a utility feature found in VMware vSphere which effectively eliminates the need to have dedicated standby hardware and software for a virtualized computing environment.
It can maximize availability or uptime across the virtualized infrastructure by reducing unplanned downtimes and eliminating planned downtime due to maintenance of server and storage. This is done through monitoring of the virtual machines and the hosts which they run on, and automatically restarting failed virtual machines on other vSphere hosts when a server failure is detected as well as automatically restarting virtual machines when an operating system failure is detected.
Techopedia Explains VMware High Availability
VMware High Availability makes use of the master-slave node relationship model which replaces the old primary and secondary node cluster model. Availability actions are controlled by a master node which relays all states and activities to the VMware vCenter Server. This eliminates much of the required planning when designing a high-availability environment since administrators no longer need to worry about which nodes are to be made primary and where they should be located.
VMware HA offers reliability since it has no external dependencies to DNS resolution, which greatly reduces the chances that an external component outage affects the system. VMware HA also uses multiple communication paths to increase redundancy in case one path goes down.