What is Clustering and why is cluster software needed?
A cluster is a group of independent servers used in a network that cooperate as a single system. Clustering is a technique used to create a highly available and easily scalable environment. Cluster software is the software running on each of these servers that provides the intelligence, which enables the coordinated cooperation of those servers. If one of the cluster servers fails, the work previously running on that server can be restarted on another available server in the cluster.