Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Planning and Documenting an HA Cluster
Cluster Configuration Planning
Chapter 4116
HEARTBEAT_INTERVAL
The normal interval between the transmission of
heartbeat messages from one node to the other in the
cluster. Enter a number of microseconds. The default
value is 1,000,000 microseconds; setting the parameter
to a value less than the default is not recommended.
The default should be used where possible. The
maximum value recommended is 15 seconds, and the
maximum value supported is 30 seconds or half the
value of NODE_TIMEOUT (below).
Can be changed while the cluster is running.
NODE_TIMEOUT
The time, in microseconds, after which a node may
decide that another node has become unavailable and
initiate cluster reformation.
Maximum value: 60,000,000 microseconds (60
seconds).
Minimum value: 2 * HEARTBEAT_INTERVAL
Default value: 2,000,000 microseconds (2 seconds).
Recommendations: You need to decide whether it's
more important for your installation to have fewer
cluster reformations, or faster reformations:
• To ensure the fastest cluster reformations, use the
default value. But keep in mind that this setting
can lead to reformations that are caused by
short-lived system hangs or network load spikes.
• For fewer reformations, use a setting in the range
of 5,000,000 to 8,000,000 microseconds (5 to 8
seconds). But keep in mind that this will lead to
slower reformations than the default value.
• The maximum recommended value is 30,000,000
microseconds (30 seconds).
Remember that a cluster reformation may result in a
system reboot on one of the cluster nodes.