1장. High Availability Add-On overview

The High Availability Add-On is a clustered system that provides reliability, scalability, and availability to critical production services.

High availability clusters, sometimes called failover clusters, provide highly available services by eliminating single points of failure and by failing over services from one cluster node to another in case a node becomes inoperative. Typically, services in a high availability cluster read and write data by means of read-write mounted file systems. A high availability cluster must maintain data integrity as one cluster node takes over control of a service from another cluster node. Node failures in a high availability cluster are not visible from clients outside the cluster. The High Availability Add-On provides high availability clustering through its high availability service management component, Pacemaker.

Pacemaker is the cluster resource manager for the High Availability Add-On. It achieves maximum availability for your cluster services and resources by making use of the cluster infrastructure’s messaging and membership capabilities to deter and recover from node and resource-level failure.

Red Hat provides a variety of documentation for planning, configuring, and maintaining a Red Hat high availability cluster. For a listing of articles that provide guided indexes to the various areas of Red Hat cluster documentation, see the Red Hat Knowledgebase article Red Hat High Availability Add-On Documentation Guide.