Managing Serviceguard A.11.20, March 2013

15.145.162.131 gryf.uksr.hp.com gryf
10.8.0.131 gryf2.uksr.hp.com gryf
10.8.1.131 gryf3.uksr.hp.com gryf
15.145.162.132 sly.uksr.hp.com sly
10.8.0.132 sly2.uksr.hp.com sly
10.8.1.132 sly3.uksr.hp.com sly
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 aliases alias-node1 and alias-node2, then the entries in /etc/
hosts should look something like this:
15.145.162.131 gryf.uksr.hp.com gryf alias-node1
10.8.0.131 gryf2.uksr.hp.com gryf alias-node1
10.8.1.131 gryf3.uksr.hp.com gryf alias-node1
15.145.162.132 sly.uksr.hp.com sly alias-node2
10.8.0.132 sly2.uksr.hp.com sly alias-node2
10.8.1.132 sly3.uksr.hp.com sly alias-node2
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 111).
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 333).)
NOTE: If you plan to use cmpreparecl (1m) (orcmpdeploycl (1m), which calls
cmpreparecl), the /etc/hosts and /etc/nsswitch.confconfiguration described the
procedure that follows will be done automatically, but you should still read the entire subsection
and make sure you understand the issues.
174 Building an HA Cluster Configuration