Managing Serviceguard Fifteenth Edition, reprinted May 2008

Planning and Documenting an HA Cluster
Cluster Configuration Planning
Chapter 4 165
HEARTBEAT_INTERVAL
The normal interval, in microseconds, between the
transmission of heartbeat messages from each node to
the cluster coordinator.
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 recommended value is 15 seconds and the
maximum value supported is 30 seconds or half the
NODE_TIMEOUT.
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 reset on one of the cluster nodes. For further
discussion, see“What Happens when a Node Times
Out” on page 126.