Managing HP Serviceguard A.11.20.20 for Linux, March 2014

IMPORTANT: Serviceguard does not support aliases for IPv6 addresses.
For information about configuring an IPv6–only cluster, or a cluster that uses a combination of IPv6
and IPv4 addresses for the nodes' hostnames, see “About Hostname Address Families: IPv4-Only,
IPv6-Only, and Mixed Mode” (page 88).
5.1.5.1 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.
The procedure that follows shows how to create a robust name-resolution configuration that will
allow cluster nodes to continue communicating with one another if a name service fails.
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; see “Configuring Name
Resolution” (page 137) for discussion and examples.
NOTE: For each cluster node, the public-network IP address must be the first address listed.
This enables other applications to talk to other nodes on public networks.
2. If you are using DNS, make sure your name servers are configured in /etc/resolv.conf,
for example:
domain cup.hp.com
search cup.hp.com hp.com
nameserver 15.243.128.51
nameserver 15.243.160.51
3. Edit or create the /etc/nsswitch.conf file on all nodes and add the following text, if it
does not already exist:
• for DNS, enter (two lines) :
hosts: files [NOTFOUND=continue UNAVAIL=continue] dns [NOTFOUND=return UNAVAIL=return]
• for NIS, enter (two lines) :
hosts: files [NOTFOUND=continue UNAVAIL=continue] nis [NOTFOUND=return UNAVAIL=return]
If a line beginning with the string hosts: already exists, then make sure that the text
immediately to the right of this string is (on one line):
files [NOTFOUND=continue UNAVAIL=continue] dns [NOTFOUND=return UNAVAIL=return]
or
files [NOTFOUND=continue UNAVAIL=continue] nis [NOTFOUND=return UNAVAIL=return]
This step is critical, allowing the cluster nodes to resolve hostnames to IP addresses while DNS,
NIS, or the primary LAN is down.
4. Create a $SGCONF/cmclnodelist file on all nodes that you intend to configure into the
cluster, and allow access by all cluster nodes. See “Allowing Root Access to an Unconfigured
Node” (page 136).
5.1 Preparing Your Systems 139