Installation guide

Section 2.3:Steps for Installing and Configuring the Red Hat Linux Distribution 35
• Do not place local file systems, such as /, /etc, /tmp, and /var on shared disks or on the same
SCSI bus as shared disks. This helps prevent the other cluster member from accidentally mounting
these file systems, and also reserves the limited number of SCSI identification numbers on a bus
for cluster disks.
• Place /tmp and /var on different file systems. This may improve system performance.
• When a cluster system boots, be sure that the system detects the disk devices in the same order in
which they were detected during the Linux installation. If the devices are not detected in the same
order, the system may not boot.
• When using RAID storage configured with Logical Unit Numbers (LUNs) greater than zero, it is
necessary to enable LUN support by adding the following to /etc/modules.conf:
options scsi_mod max_scsi_luns=255
After modifying modules.conf, it is necessary to rebuild the initial ram disk using mkinitrd.
Refer to the Official Red Hat Linux Customization Guide for more information about creating
ramdisks using mkinitrd.
2.3.2 Editing the /etc/hosts File
The /etc/hosts file contains the IP address-to-hostname translation table. The /etc/hosts file
on each cluster system must contain entries for the following:
• IP addresses and associated host names for both cluster systems
• IP addresses and associated host names for the point-to-point Ethernet heartbeat connections (these
can be private IP addresses)
As an alternative to the /etc/hosts file, naming services such as DNS or NIS can be used to define
the host names used by a cluster. However, to limit the number of dependencies and optimize avail-
ability, it is strongly recommended to use the /etc/hosts file to define IP addresses for cluster
network interfaces.
The following is an example of an /etc/hosts file on a cluster system:
127.0.0.1 localhost.localdomain localhost
193.186.1.81 cluster2.yourdomain.com cluster2
10.0.0.1 ecluster2.yourdomain.com ecluster2
193.186.1.82 cluster3.yourdomain.com cluster3
10.0.0.2 ecluster3.yourdomain.com ecluster3
193.186.1.83 clusteralias.yourdomain.com clusteralias
The previous example shows the IP addresses and host names for two cluster systems (cluster2 and
cluster3), and the private IP addresses and host names for the Ethernet interface used for the point-to-