Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Building an HA Cluster Configuration
Preparing Your Systems
Chapter 5 147
NOTE Serviceguard recognizes only the hostname (the first element) in a fully
qualified domain name (a name with four elements separated by
periods, like those in the example above). This means, for example, that
gryf.uksr.hp.com and gryf.cup.hp.com cannot be nodes in the same
cluster, as Serviceguard would see them as the same host gryf.
If applications require the use of hostname aliases, the Serviceguard
hostname must be one of the aliases in all the entries for that host. For
example, if the two-node cluster in the previous example were configured
to use the alias hostnames alias-node1 and alias-node2, then the
entries in /etc/hosts should look something like this:
15.145.162.131 gryf.uksr.hp.com gryf1 alias-node1
10.8.0.131 gryf2.uksr.hp.com gryf2 alias-node1
10.8.1.131 gryf3.uksr.hp.com gryf3 alias-node1
15.145.162.132 sly.uksr.hp.com sly1 alias-node2
10.8.0.132 sly2.uksr.hp.com sly2 alias-node2
10.8.1.132 sly3.uksr.hp.com sly3 alias-node2
Safeguarding against Loss of Name Resolution Services
When you employ any user-level Serviceguard command (including
cmviewcl), the command uses the name service you have configured
(such as DNS) to obtain the addresses of all the cluster nodes. If the
name service is not available, the command could hang or return an
unexpected networking error message.
NOTE If such a hang or error occurs, Serviceguard and all protected
applications will continue working even though the command you issued
does not. That is, only the Serviceguard configuration commands (and
corresponding Serviceguard Manager functions) are affected, not the
cluster daemon or package services.