Managing Serviceguard 13th Edition, February 2007

Building an HA Cluster Configuration
Preparing Your Systems
Chapter 5 203
Serviceguard has also been tested with non-default values for these two
network parameters:
• ip6_nd_dad_solicit_count - This network parameter enables the
Duplicate Address Detection feature for IPv6 address. For more
information, see “IPv6 Relocatable Address and Duplicate Address
Detection Feature” on page 468 of this manual.
• tcp_keepalive_interval - This network parameter controls the
length of time the node will allow an unused network socket to exist
before reclaiming its resources so they can be reused.
The following requirements must be met:
— The maximum value for tcp_keepalive_interval is 7200000 (2
hours, the HP-UX default value).
— The minimum value for tcp_keepalive_interval is 60000 (60
seconds).
—The tcp_keepalive_interval value must be set on a node
before Serviceguard is started on that node. This can be done by
configuring the new tcp_keepalive_interval in the
/etc/rc.config.d/nddconf file, which will automatically set
any ndd parameters at system boot time.
—The tcp_keepalive_interval value must be the same for all
nodes in the cluster.
Preparing 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 may 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.