Managing Serviceguard Fifteenth Edition, reprinted May 2008

Building an HA Cluster Configuration
Configuring the Cluster
Chapter 5 237
Specifying Maximum Number of Configured Packages
This specifies the most packages that can be configured in the cluster.
The parameter 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.
As of Serviceguard A.11.17, the default is 150, which is the maximum
allowable number of packages in a cluster.
NOTE Remember to tune HP-UX 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 Cluster Timing Parameters
The cmquerycl command supplies default cluster timing parameters for
HEARTBEAT_INTERVAL and NODE_TIMEOUT. Changing these parameters
will directly affect the cluster’s reformation and failover times. It is
useful to modify these parameters if the cluster is re-forming
occasionally because of heavy system load or heavy network traffic; you
can do this while the cluster is running.
The default value of 2 seconds for NODE_TIMEOUT leads to a best case
failover time of 30 seconds. If NODE_TIMEOUT is changed to 10 seconds,
which means that the cluster manager waits 5 times longer to timeout a
node, the failover time is increased by 5, to approximately 150 seconds.
NODE_TIMEOUT must be at least twice HEARTBEAT_INTERVAL. A good rule
of thumb is to have at least two or three heartbeats within one
NODE_TIMEOUT.
For more information about node timeouts, see “What Happens when a
Node Times Out” on page 126 and the HEARTBEAT_INTERVAL and
NODE_TIMEOUT parameter discussions under “Cluster Configuration
Parameters” starting on page 156.