Installation guide

2 Chapter 1. Red Hat Cluster Suite Overview

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 High-availability Service Manage-

ment component.

Load-balancing clusters dispatch network service requests to multiple cluster nodes to bal-

ance the request load among the cluster nodes. Load balancing provides cost-effective scal-

ability because you can match the number of nodes according to load requirements. If a

node in a load-balancing cluster becomes inoperative, the load-balancing software detects

the failure and redirects requests to other cluster nodes. Node failures in a load-balancing

cluster are not visible from clients outside the cluster. Red Hat Cluster Suite provides load-

balancing through LVS (Linux Virtual Server).

High-performance clusters use cluster nodes to perform concurrent calculations. A high-

performance cluster allows applications to work in parallel, therefore enhancing the perfor-

mance of the applications. (High performance clusters are also referred to as computational

clusters or grid computing.)

Note

The cluster types summarized in the preceding text reﬂect basic conﬁgurations; your

needs might require a combination of the clusters described.

1.2. Red Hat Cluster Suite Introduction

Red Hat Cluster Suite (RHCS) is an integrated set of software components that can be de-

ployed in a variety of conﬁgurations to suit your needs for performance, high-availability,

load balancing, scalability, ﬁle sharing, and economy.

RHCS consists of the following major components (refer to Figure 1-1):

• Cluster infrastructure — Provides fundamental functions for nodes to work together as

a cluster: conﬁguration-ﬁle management, membership management, lock management,

and fencing.

• High-availability Service Management — Provides failover of services from one cluster

node to another in case a node becomes inoperative.