High-Availability Cluster

High-availability clusters (also known as HA Clusters) are computer clusters that are implemented primarily for the purpose of improving the availability of services which the cluster provides. They operate by having redundant computers or nodes which are then used to provide service when system components fail.

HA clusters are often used for key databases, file sharing on a network, business applications, and customer services such as electronic commerce websites.

HA cluster implementations attempt to build redundancy into a cluster to eliminate single points of failure, including multiple network connections and data storage which is multiply connected via Storage area networks.

HA clusters usually use a heartbeat private network connection which is used to monitor the health and status of each node in the cluster.

The Linux-HA (High-Availability Linux) project provides a high-availability (clustering) solution for Linux, FreeBSD, Solaris which promotes reliability, availability, and serviceability (RAS).