Managing Serviceguard 14th Edition, June 2007

Building an HA Cluster Configuration
Managing the Running Cluster
Chapter 5266
Preventing Automatic Activation of LVM Volume
Groups
It is important to prevent LVM volume groups that are to be used in
packages from being activated at system boot time by the /etc/lvmrc
file. One way to ensure that this does not happen is to edit the
/etc/lvmrc file on all nodes, setting AUTO_VG_ACTIVATE to 0, then
including all the volume groups that are not cluster-bound in the
custom_vg_activation function. Volume groups that will be used by
packages should not be included anywhere in the file, since they will be
activated and deactivated by control scripts.
NOTE Special considerations apply in the case of the root volume group:
• If the root volume group is mirrored using MirrorDisk/UX, include it
in the custom_vg_activation function so that any stale extents in
the mirror will be re-synchronized.
• Otherwise, the root volume group does not need to be included in the
custom_vg_activation function, because it is automatically
activated before the /etc/lvmrc file is used at boot time.
Setting up Autostart Features
Automatic startup is the process in which each node individually joins a
cluster; Serviceguard provides a startup script to control the startup
process. Automatic cluster start is the preferred way to start a cluster.
No action is required by the system administrator.
There are three cases:
• The cluster is not running on any node, all cluster nodes must be
reachable, and all must be attempting to start up. In this case, the
node attempts to form a cluster consisting of all configured nodes.
• The cluster is already running on at least one node. In this case, the
node attempts to join that cluster.
• Neither is true: the cluster is not running on any node, and not all
the nodes are reachable and trying to start. In this case, the node will
attempt to start for the AUTO_START_TIMEOUT period. If neither of
these things becomes true in that time, startup will fail.