HP manual Single-Node Operation, Disabling Serviceguard, Removing Serviceguard from a System

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.

Disabling Serviceguard

If for some reason you want to disable Serviceguard on a system, you can do so by commenting out the following entries in /etc/inetd.conf:

hacl-cfg dgram udp wait root /usr/lbin/cmclconfd cmclconfd -p hacl-cfg stream tcp nowait root /usr/lbin/cmclconfd cmclconfd -c

Then force inetd to re-read inetd.conf:

/usr/sbin/inetd -c

You can check that this did in fact disable Serviceguard by trying the following command:

cmquerycl -n nodename

where nodename is the name of the local system. If the command fails, you have successfully disabled Serviceguard.

NOTE: You should not disable Serviceguard on a system on which it is actually running. If you are not sure, you can get an indication by means of the command:

ps -e grep cmclconfd

If there are cmclconfd processes running, it does not mean for certain that Serviceguard is running on this system (cmclconfd could simply be handling UDP queries from a Serviceguard cluster on the same subnet) but it does mean you should investigate further before disabling Serviceguard.

Removing Serviceguard from a System

To remove Serviceguard from a node, use the swremove command.

CAUTION: Remove the node from the cluster first. If you run the swremove command on a server that is still a member of a cluster, it will cause that cluster to halt, and the cluster configuration to be deleted.

To remove Serviceguard:

1.If the node is an active member of a cluster, halt the node.

2.If the node is included in a cluster configuration, remove the node from the configuration.

3.If you are removing Serviceguard from more than one node, issue swremove on one node at a time.

320 Cluster and Package Maintenance