Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Planning and Documenting an HA Cluster
Planning for Changes in Cluster Size
Chapter 4140
Planning for Changes in Cluster Size
If you intend to add additional nodes to the cluster online (while it is
running) ensure that they are connected to the same heartbeat subnets
and to the same lock disks as the other cluster nodes.
In selecting a cluster lock configuration, be careful to anticipate any
potential need for additional cluster nodes. Remember that while a
two-node cluster must use a cluster lock, a cluster of more than four
nodes must not use a lock LUN, but can use a quorum server. So if you
will eventually need five nodes, you should build an initial configuration
that uses a quorum server.
If you intend to remove a node from the cluster configuration while the
cluster is running, ensure that the resulting cluster configuration will
still conform to the rules for cluster locks described above. See “Cluster
Lock Planning” on page 104 for more information.
If you are planning to add a node online, and a package will run on the
new node, ensure that any existing cluster-bound volume groups for the
package have been imported to the new node. Also, ensure that the
MAX_CONFIGURED_PACKAGES parameter (see “Cluster Configuration
Parameters” starting on page 110) is set high enough to accommodate
the total number of packages you will be using.