VCS is a high availability cluster solution developed by veritas. It will get rid of downtime by switching to other servers in case of a failure in a server.
It uses the heartbeat technology.
The Veritas Cluster Server is commonly used in datacenters.With the VCS installed in the case of a fault, the VCS takes action accordingly and the applications recover automatically. When your website happens to go down the VCS helps you restart those applications at another datacenter. In case of even the worst disaster your website remains up and running.
Have a look at the link:
http://eval.veritas.com/downloads/van/vcs_quickref.pdf