Managing Serviceguard Sixteenth Edition, March 2009

IMPORTANT: Serviceguard does not support aliases for IPv6 addresses. For more
information about configuring a combination of IPv6 and IPv4 addresses, see the
discussion of the HOSTNAME_ADDRESS_FAMILY parameter under “Cluster
Configuration Parameters ” (page 138).
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. If a standby LAN is configured, this approach also allows the cluster to
continue to function fully (including commands such as cmrunnode and cmruncl)
after the primary LAN has failed.
NOTE: If a NIC fails, the affected node will be able to fail over to a standby LAN so
long as the node is running in the cluster. But if a NIC that is used by Serviceguard
fails when the affected node is not running in the cluster, Serviceguard will not be able
to restart the node. (For instructions on replacing a failed NIC, see “Replacing LAN or
Fibre Channel Cards” (page 368).)
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 196) 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
198 Building an HA Cluster Configuration