Single-Node Operation

In a multi-node cluster, you could have a situation in which all but one node has failed, or you have shut down all but one node, leaving your cluster in single-node operation. This remaining node will probably have applications running on it. As long as the Serviceguard daemon cmcld is active, other nodes can rejoin the cluster.

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.

You should not try to restart Serviceguard, since data corruption might occur if another node were to attempt to start up a new instance of the application that is still running on the single node.

Instead of restarting the cluster, choose an appropriate time to shut down the applications and reboot the node; this will allow Serviceguard to restart the cluster after the reboot.