HP Serviceguard A.11.20- Managing Serviceguard Twentieth Edition, August 2011

Automatically Restarting the Cluster
You can configure your cluster to automatically restart after an event, such as a long-term power
failure, which brought down all nodes in the cluster. This is done by setting AUTOSTART_CMCLD
to 1 in the /etc/rc.config.d/cmcluster file.
Halting a Node or the Cluster while Keeping Packages Running
There may be circumstances in which you want to do maintenance that involves halting a node,
or the entire cluster, without halting or failing over the affected packages. Such maintenance might
consist of anything short of rebooting the node or nodes, but a likely case is networking changes
that will disrupt the heartbeat.
New command options in Serviceguard A.11.20 (collectively known as Live Application Detach
(LAD)) allow you to do this kind of maintenance while keeping the packages running. The packages
are no longer monitored by Serviceguard, but the applications continue to run. Packages in this
state are called detached packages.
When you have done the necessary maintenance, you can restart the node or cluster, and normal
monitoring will resume on the packages.
NOTE: Keep in mind that the purpose of the LAD capabilities is to allow you do maintenance
on one or more nodes, or the entire cluster. If you want to do maintenance on individual packages,
or on elements of the cluster configuration that affect only one package, or a few packages, you
should probably use package maintenance mode; see “Maintaining a Package: Maintenance
Mode” (page 287).
What You Can Do
You can do the following.
• Halt a node (cmhaltnode (1m) with the -d option) without causing its running packages
to halt or fail over.
Until you restart the node (cmrunnode (1m)) these packages are detached — not being
monitored by Serviceguard.
• Halt the cluster (cmhaltcl (1m) with the -d option) without causing its running packages
to halt.
Until you restart the cluster (cmruncl (1m)) these packages are detached — not being
monitored by Serviceguard.
• Halt a detached package, including instances of detached multi-node packages.
• Restart normal package monitoring by restarting the node (cmrunnode) or the cluster
(cmruncl).
Rules and Restrictions
The following rules and restrictions apply.
• All the nodes in the cluster must be running A.11.20.
• All the configured cluster nodes must be reachable by an available network (not necessarily
a network that is configured into the cluster).
• You must be root user (superuser) to halt or start a node or cluster with Live Application Detach,
and to halt a detached package.
• Live Application Detach is not supported for SGeRAC clusters configured with SLVM or ASM.
• Live Application Detach is not supported for clusters using the Veritas Cluster Volume Manager
(CVM) or Cluster File System (CFS).
280 Cluster and Package Maintenance