Managing Serviceguard 12th Edition, March 2006

Building an HA Cluster Configuration
Managing the Running Cluster
Chapter 5266
Single-Node Operation
Single-node operation occurs in a single-node cluster or in a multi-node
cluster, following a situation where all but one node has failed, or where
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 re-join the cluster at a later time.
If the Serviceguard daemon fails when in single-node operation, it will
leave the single node up and your applications running. This is different
from the loss of the Serviceguard daemon in a multi-node cluster, which
halts the node with a TOC, and causes packages to be switched to
adoptive nodes.
It is not necessary to halt the single node in this scenario, since the
application is still running, and no other node is currently available for
package switching.
However, you should
not try to restart Serviceguard, since data
corruption might occur if the node were to attempt to start up a new
instance of the application that is still running on the node. Instead of
restarting the cluster, choose an appropriate time to shutdown and
reboot the node, which will allow the applications to shut down and then
permit Serviceguard to restart the cluster after rebooting.
Deleting the Cluster Configuration
With root login, you can delete a cluster configuration from all cluster
nodes by using Serviceguard Manager, or on the command line. The
cmdeleteconf command prompts for a verification before deleting the
files unless you use the -f option. You can only delete the configuration
when the cluster is down. The action removes the binary configuration
file from all the nodes in the cluster and resets all cluster-aware volume
groups to be no longer cluster-aware.
NOTE The cmdeleteconf command removes only the cluster binary file
/etc/cmcluster/cmclconfig. It does not remove any other files from
the /etc/cmcluster directory.