Managing HP Serviceguard for Linux, Tenth Edition, September 2012

IMPORTANT: Note that in this example subnet 15.244.65.0, used by NodeA and
NodeB, is not routed to 15.244.56.0, used by NodeC and NodeD.
But subnets 15.13.164.0 and 15.13.165.0, used by NodeA and NodeB, are routed
respectively to subnets 15.13.172.0 and 15.13.182.0, used by NodeC and NodeD.
At least one such routing among all the nodes must exist for cmquerycl to succeed.
For information about configuring the heartbeat in a cross-subnet configuration, see the
HEARTBEAT_IP parameter discussion under “Cluster Configuration Parameters ”
(page 103).
Identifying Heartbeat Subnets
The cluster configuration file includes entries for IP addresses on the heartbeat subnet.
HP recommends that you use a dedicated heartbeat subnet, and configure heartbeat on
other subnets as well, including the data subnet.
The heartbeat can be on an IPv4 or an IPv6 subnet.
The heartbeat can comprise multiple IPv4 subnets joined by a router. In this case at least
two heartbeat paths must be configured for each cluster node. See also the discussion
of HEARTBEAT_IP (page 109), and “Cross-Subnet Configurations” (page 27).
Specifying Maximum Number of Configured Packages
This value must be equal to or greater than the number of packages currently configured
in the cluster. The count includes all types of packages: failover, multi-node, and system
multi-node. The maximum number of packages per cluster is 300. The default is the
maximum.
NOTE: Remember to tune kernel parameters on each node to ensure that they are set
high enough for the largest number of packages that will ever run concurrently on that
node.
Modifying the MEMBER_TIMEOUT Parameter
The cmquerycl command supplies a default value of 14 seconds for the
MEMBER_TIMEOUT parameter. Changing this value will directly affect the cluster’s
re-formation and failover times. You may need to increase the value if you are
experiencing cluster node failures as a result of heavy system load or heavy network
traffic; or you may need to decrease it if cluster re-formations are taking a long time.
You can change MEMBER_TIMEOUT while the cluster is running.
For more information about node timeouts, see “What Happens when a Node Times
Out” (page 87) and the MEMBER_TIMEOUT parameter discussions under “Cluster
Configuration Parameters ” (page 103), and “Cluster Re-formations Caused by
MEMBER_TIMEOUT Being Set too Low” (page 300).
Configuring the Cluster 185