OCFS2 Integration with HP Serviceguard for Linux Administrator's Guide, Second Edition, May 2009

Figure 2-2 OCFS2 Network Idle Timeout Definitions
In the figure, t0, t1, t2, t3, and t4 represent the time at which HP Serviceguard for Linux and
OCFS2 realize that there is a network failure. Following is the sequence of events:
1. At t0, network links that carry the Serviceguard heartbeat, OCFS2 data, and the TCP
connection is lost.
2. At t1, HP Serviceguard for Linux recognizes that there is a network failure, due to the loss
of the heartbeat.
3. At t2, the node times out, and HP Serviceguard transfers control of the node, forcing it to
restart and rejoin the cluster.
4. At t3, the Serviceguard Cluster Manager forms a stable cluster with the remaining nodes.
5. At t4, OCFS2 realizes that there is a network failure. But at this time, Serviceguard has
already formed a stable cluster.
The time interval between t0 and t3 is known as the Serviceguard Cluster Reconfiguration Time
(CRT). It is recommended that the value of the OCFS2 Network Idle Timeout parameter be set
to 20 seconds more than the time taken by Serviceguard to form a stable cluster. Use the following
formula to determine the value to be set for the O2CB_NET_IDLE_TIMEOUT parameter:
O2CB_NET_IDLE_TIMEOUT = [Serviceguard Cluster Reconfiguration Time (in
seconds) + 20 seconds] x 1000
For example:
If an HP Serviceguard cluster with 4 nodes is configured with a default heartbeat of 1 second
and a node timeout value of 2 seconds, then a stable cluster is formed in about 28 seconds. So
according to figure 1, the time period between t0 and t3 is 28 seconds. So, using the formula, the
O2CB_NET_IDLE_TIMEOUT parameter is set to 48000 milliseconds.
O2CB_IDLE_TIMEOUT_MS = (28 seconds + 20 seconds) x 1000
O2CB_IDLE_TIMEOUT_MS = 48000 milliseconds
Table 2-1 lists the various heartbeat intervals of HP Serviceguard A.11.18, along with the
corresponding cluster reconfiguration time and the recommended values for the
O2CB_NET_IDLE_TIMEOUT values. Table 2-2 (page 20) lists the various heartbeat intervals of
HP Serviceguard A.11.19, along with corresponding cluster reconfiguration time. Use these tables
to configure the values of the O2CB_NET_IDLE_TIMEOUT parameter.
Pre-configuration Steps 19