Red Hat ENTERPRISE LINUX 5 - ADMINISTRATION Manual page 28

Chapter 2. Before Configuring a Red Hat Cluster
Figure 2.1. Web Server Cluster Service Example
Clients access the HA service through the IP address 10.10.10.201, enabling interaction with the web
server application, httpd-content. The httpd-content application uses the gfs-content-webserver file
system. If node B were to fail, the content-webserver HA service would fail over to node D. If node
D were not available or also failed, the service would fail over to node A. Failover would occur with
minimal service interruption to the cluster clients. For example, in an HTTP service, certain state
information may be lost (like session data). The HA service would be accessible from another cluster
node via the same IP address as it was before failover.
Note
For more information about HA services and failover domains, refer to Red Hat Cluster
Suite Overview. For information about configuring failover domains, refer to
"Configuring a Failover Domain"
Domain"
(using system-config-cluster).
An HA service is a group of cluster resources configured into a coherent entity that provides
specialized services to clients. An HA service is represented as a resource tree in the cluster
configuration file, /etc/cluster/cluster.conf (in each cluster node). In the cluster configuration
18
(using Conga) or Section 5.6, "Configuring a Failover
Section 3.7,