VMWare High Availability or HA is another Virtual Infrastructure 3 component that adds tremendous value to the product line. This product in earlier versions was known as DAS or Distributed Availability Services. High availaility allows Virtual Machines to failover automatically between ESX hosts in the same cluster. This article will give an overview of the product and help you decide on the value it can add to your business.

VMWare HA is something that we have been waiting for now since the original release of ESX. The High Availability component leverages the technology of Virtual Center, ESX server and shared storage to provide value to the business. It provides this value by maximising service uptime. The administrator has many options for configuration and management of HA. right down to customising behaviour for each of the virtual machines.

While the high availability option was available before if you were a guru and could do some nice scripting and cron jobs, it was not for the average administrator. The reason behind this was the design of the virtual machine configuration in earlier versions of ESX server. The configuration file associated with the VM's, the .vmx file was stored individually on the host it ran on. In Virtual Infrastructure 3 it now lives on shared storage. This enables multiple hosts to access that file should the host it is running on crash or go down.