Installation guide

Section A.7:Tuning the Failover Interval 169

Name Default (sec.) Description

sameTimeNetdown

The number of intervals that must elapse before

concluding a cluster member has failed when

the cluhbd heartbeat daemon is unable to

communicate with the other cluster member

sameTimeNetup

12 The number of intervals that must elapse before

concluding a cluster member to have failed,

when the cluhbd heartbeat daemon is able to

communicate with the other cluster member. The

value of this parameter must be greater than the

sameTimeNetdown parameter.

For example, suppose one cluster member has a hardware fault and ceases to function. In this case,

both cluquorumd and cluhbd will agree that the other cluster member has failed. After a period

of (pingInterval * sameTimeNetdown), (which by default is 14 seconds total), the failover will com-

mence.

In order to tune this failover interval, the cludb utility is used. For example, to modify the failover

interval down to a duration of 10 seconds, rather than the default of 14 seconds, the value of the same-

TimeNetdown parameter should be set to 5 as follows:

cludb -p cluquorumd%sameTimeNetdown 5

Note

Caution should be used when tuning these parameters. If a specified failover

interval is too small, there is risk of incorrectly concluding that a member has

failed during spikes in activity.

Also note that if the power switch type "watchdog" is in use, it is necessary

that the watchdog expiration interval be less than the failover interval. It

is recommended that the watchdog interval be set to approximately 2/3 the

duration of the failover interval.