Managing HP Serviceguard for Linux, Tenth Edition, September 2012

Manual Startup of Entire Cluster
A manual startup forms a cluster out of all the nodes in the cluster configuration. Manual
startup is normally done the first time you bring up the cluster, after cluster-wide
maintenance or upgrade, or after reconfiguration.
Before startup, the same binary cluster configuration file must exist on all nodes in the
cluster. The system administrator starts the cluster with the cmruncl command issued
from one node. The cmruncl command can only be used when the cluster is not running,
that is, when none of the nodes is running the cmcld daemon.
During startup, the cluster manager software checks to see if all nodes specified in the
startup command are valid members of the cluster, are up and running, are attempting
to form a cluster, and can communicate with each other. If they can, then the cluster
manager forms the cluster.
Automatic Cluster Startup
An automatic cluster startup occurs any time a node reboots and joins the cluster. This
can follow the reboot of an individual node, or it may be when all nodes in a cluster
have failed, as when there has been an extended power failure and all SPUs went down.
Automatic cluster startup will take place if the flag AUTOSTART_CMCLD is set to 1 in the
$SGCONF/cmcluster.rc file. When any node reboots with this parameter set to 1,
it will rejoin an existing cluster, or if none exists it will attempt to form a new cluster.
Dynamic Cluster Re-formation
A dynamic re-formation is a temporary change in cluster membership that takes place
as nodes join or leave a running cluster. Re-formation differs from reconfiguration, which
is a permanent modification of the configuration files. Re-formation of the cluster occurs
under the following conditions (not a complete list):
• An SPU or network failure was detected on an active node.
• An inactive node wants to join the cluster. The cluster manager daemon has been
started on that node.
• A node has been added to or deleted from the cluster configuration.
• The system administrator halted a node.
• A node halts because of a package failure.
• A node halts because of a service failure.
• Heavy network traffic prohibited the heartbeat signal from being received by the
cluster.
• The heartbeat network failed, and another network is not configured to carry
heartbeat.
How the Cluster Manager Works 39