Managing HP Serviceguard A.11.20.10 for Linux, December 2012

NOTE: The /sbin/init.d/cmcluster file may call files that Serviceguard stores in$SGCONF/
rc. (See “Understanding the Location of Serviceguard Files” (page 129) for information about
Serviceguard directories on different Linux distributions.) This directory is for Serviceguard use
only! Do not move, delete, modify, or add files in this directory.
5.3.3 Changing the System Message
You may find it useful to modify the system's login message to include a statement such as the
following:
This system is a node in a high availability cluster.
Halting this system may cause applications and services to
start up on another node in the cluster.
You may want to include a list of all cluster nodes in this message, together with additional
cluster-specific information.
The /etc/motd file may be customized to include cluster-related information.
5.3.4 Managing a Single-Node Cluster
The number of nodes you will need for your cluster depends on the processing requirements of the
applications you want to protect.
In a single-node cluster, a quorum server is not required, since there is no other node in the cluster.
The output from the cmquerycl command omits the quorum server information area if there is
only one node.
You still need to have redundant networks, but you do not need to specify any heartbeat LANs,
since there is no other node to send heartbeats to. In the cluster configuration file, specify all LANs
that you want Serviceguard to monitor. For LANs that already have IP addresses, specify them
with the STATIONARY_IP parameter, rather than the HEARTBEAT_IP parameter.
5.3.4.1 Single-Node Operation
Single-node operation occurs in a single-node cluster, or in a multi-node cluster in which all but
one node has failed, or in which you have shut down all but one node, which will probably have
applications running. As long as the Serviceguard daemon cmcld is active, other nodes can rejoin
the cluster at a later time.
If the cmcld daemon fails during single-node operation, it will leave the single node up and your
applications running. (This is different from the failure of cmcld in a multi-node cluster, which
causes the node to halt with a reboot, and packages to be switched to adoptive nodes.)
It is not necessary to halt the single node in this case, since the applications are still running, and
no other node is currently available for package switching.
CAUTION: But you should not try to restart Serviceguard; data corruption might occur if another
node were to attempt to start up a new instance of an application that is still running on the single
node. Instead, choose an appropriate time to shut down and reboot the node. This will allow the
applications to shut down and Serviceguard to restart the cluster after the reboot.
5.3.5 Disabling identd
Ignore this section unless you have a particular need to disable identd.
You can configure Serviceguard not to use identd.
CAUTION: This is not recommended. Consult the white paper Securing Serviceguard at http://
www.hp.com/go/hpux-serviceguard-docs (Select HP Serviceguard -> White Papers) for more
information.
160 Building an HA Cluster Configuration