Managing Serviceguard Fifteenth Edition, reprinted May 2008

Planning and Documenting an HA Cluster
Planning for Changes in Cluster Size
Chapter 4 195
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 a cluster of
more than four nodes must not use a lock disk, but a two-node cluster
must use a cluster lock. Thus, 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 145 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 156) is set high enough to accommodate
the total number of packages you will be using.