Red Hat Cluster Suite Overview; Cluster Basics; Cluster Administration - Red Hat ENTERPRISE LINUX 4 Manual

Chapter 1.

Red Hat Cluster Suite Overview

Clustered systems provide reliability, scalability, and availability to critical production services. Using
Red Hat Cluster Suite, you can create a cluster to suit your needs for performance, high availability,
load balancing, scalability, file sharing, and economy. This chapter provides an overview of Red Hat
Cluster Suite components and functions, and consists of the following sections:
Section 1.1, "Cluster Basics"
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Section 1.2, "Red Hat Cluster Suite Introduction"
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Section 1.3, "Cluster Infrastructure"
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Section 1.4, "High-availability Service Management"
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Section 1.5, "Red Hat GFS"
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Section 1.6, "Cluster Logical Volume Manager"
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Section 1.7, "Global Network Block Device"
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Section 1.8, "Linux Virtual Server"
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Section 1.9, "Cluster Administration Tools"
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Section 1.10, "Linux Virtual Server Administration GUI"
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1.1. 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
High-availability Service Management component.
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