A cluster denotes a group of independent servers interconnected through a dedicated network to work as one centralized data processing resource. Clustering is a popular strategy for implementing parallel processing applications. Clusters are capable of performing multiple complex instructions and it also improves systems availability to users. Computer cluster is a simple two node system which just connects two personal computers. A cluster is a logical unit of file storage on a hard disk in case of personal computer storage technology and it is managed by the computers operating system Replication means that a copy of something is produced in real time that is, copying objects from one node in a cluster to one or more other nodes in the cluster.