Managing HP Serviceguard for Linux, Tenth Edition, September 2012

# a cluster consisting of all configured nodes. Automatic cluster
# start is the preferred way to start a cluster. No action is
# required by the system administrator. If set to 1, the node will
# attempt to join/form its CM cluster automatically as described
# above. If set to 0, the node will not attempt to join its CM
# cluster.
AUTOSTART_CMCLD=1
NOTE: The /sbin/init.d/cmcluster file may call files that Serviceguard stores
in$SGCONF/rc. (See “Understanding the Location of Serviceguard Files” (page 156) 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.
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.
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.
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
196 Building an HA Cluster Configuration