Managing Serviceguard 12th Edition, March 2006

Building an HA Cluster Configuration
Preparing Your Systems
Chapter 5 199
To do this, add one of the following lines in the /etc/nsswitch.conf file:
• for DNS, enter (one line):
hosts: files [NOTFOUND=continue UNAVAIL=contine] dns
[NOTFOUND=return UNAVAIL=return]
• for NIS, enter (one line):
hosts: files [NOTFOUND=continue UNAVAIL=contine] nis
{NOTFOUND=return UNAVAIL=return]
A workaround for the problem that still retains the ability to use
conventional name lookup is to configure the /etc/nsswitch.conf file
to search the /etc/hosts file when other lookup strategies are not
working. In case name services are not available, Serviceguard
commands will then use the /etc/hosts file on the local system to do
name resolution. Of course, the names and IP addresses of all the nodes
in the cluster must be in the /etc/hosts file.
Name Resolution Following Primary LAN Failure or Loss of DNS
There are some special configuration steps required to allow cluster
configuration commands such as cmrunnode and cmruncl to continue to
work properly after LAN failure, even when a standby LAN has been
configured for the failed primary. These steps also protect against the
loss of DNS services, allowing cluster nodes to continue communicating
with one another.
1. Edit the /etc/hosts file on all nodes in the cluster. Add name
resolution for all heartbeat IP addresses, and other IP addresses
from all the cluster nodes. Example:
15.13.172.231 hasupt01
192.2.1.1 hasupt01
192.2.8.2 hasupt01
15.13.172.232 hasupt02
192.2.1.2 hasupt02
192.2.8.2 hasupt02
15.13.172.233 hasupt03
192.2.1.3 hasupt03
192.2.8.3 sgsupt03
This ensures that messages coming from non-public networks, as
well as public networks, are mapped to the correct host name.