Hello Thanks for visiting RvKmR's blogs. So, What means of clusters and why we need them. Cluster is set of servers or say computers working together to achieve single goal or a task. Now you may have idea why we need cluster. Types of Cluster: High Availability Cluster / HA Cluster HA Cluster again grouped in two types. Active-Active Cluster Active-Passive Cluster In Active-Active Cluster Service is running on all nodes in cluster. That means all nodes serving independently. In Active-Passive Cluster Service is running on one of node from cluster and other nodes in passive state. If primary node fails then only other node in cluster will start service. Storage Cluster In this cluster type, all members provides a single cluster file system that can be accessed by different servers. These file system can be used to read-write data simultaneously. EX: GFS2 OK, Then what is High Availability. This type of cluster provides high availability of serv