Cluster Basics
A cluster is two or more computers (called nodes or members) that work together to perform a task.
There are four major types of clusters:
• Storage
• High availability
• Load balancing
• High performance
Storage clusters provide a consistent file system image across servers in a cluster, allowing the
servers to simultaneously read and write to a single shared file system. A storage cluster simplifies
storage administration by limiting the installation and patching of applications to one file system.
Also, with a cluster-wide file system, a storage cluster eliminates the need for redundant copies of
application data and simplifies backup and disaster recovery. Red Hat Cluster Suite provides storage
clustering through Red Hat GFS.
High-availability clusters provide continuous availability of 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 (via read-write mounted
file systems). Therefore, 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. (High-availability clusters are sometimes referred to
as failover clusters.) Red Hat Cluster Suite provides high-availability clustering through its Highavailability
Service Management component.
Load-balancing clusters dispatch network service requests to multiple cluster nodes to balance the
request load among the cluster nodes. Load balancing provides cost-effective scalability because you
