Managing HP Serviceguard for Linux, Seventh Edition, July 2007

Building an HA Cluster Configuration
Configuring the Cluster
Chapter 5182
Modifying Cluster Timing Parameters
The cmquerycl command supplies default cluster timing parameters for
HEARTBEAT_INTERVAL and NODE_TIMEOUT. Changing these parameters
will directly impact the cluster’s reformation and failover times. It is
useful to modify these parameters if the cluster is re-forming
occasionally due to heavy system load or heavy network traffic.
The default value of two 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 five times longer to timeout
a node, the failover time is increased by five, to approximately 150
seconds. NODE_TIMEOUT must be at least twice the HEARTBEAT_INTERVAL.
A good rule of thumb is to have at least two or three heartbeats within
one NODE_TIMEOUT.
Adding or Removing Nodes While the Cluster is
Running
You can reconfigure the cluster by adding or removing nodes while the
cluster is up and running. The procedures are described in Chapter 7,
“Cluster and Package Maintenance,” on page 229.