According to the Red Hat, Red Hat Cluster Suite (RHCS) High Availability Add-On provides on-demand failover to make applications highly available. It delivers continuous availability of services by eliminating single points of failure. And clustering is a group of computers (called node or members) to work together as a team to provide continued service when system components fail.
Assume that we are running a critical database service on a standalone server, if a software or hardware component failed on that database server, administrative intervention is required and database service will be unavailable until the crashed server is fixed, but with clustering that database service get automatically restarted on another available node in the cluster without administrator invention and database service will be continuously available to the end-users. cluster can deploy as a active/active (one active node and one standby node) or active/passive (both nodes are active) to suite our clustering needs.
In this series of “RHCS - Cluster from scratch” articles, I’m planning to deeply explain how to deploy high availability web service as a active/passive cluster using Red Hat High Availability Add-On on a Red Hat Enterprise Linux 6.