[Pacemaker] proper "dampen" value for ping resource

Klaus Darilion klaus.mailinglists at pernau.at
Fri Mar 11 07:59:02 EST 2011


Hi!

I wonder what a proper value for "dampen" would be. Dampen is documented as:

# attrd_updater --help|grep dampen
 -d, --delay=value      The time to wait (dampening) in seconds further
changes occur


So, I would read this as the delay to forward changes, e.g. to not
trigger fail-over on the first failed ping, but only after multiple
failures.

Now, the default values (and examples have):

primitive pingtest ocf:pacemaker:ping \
        params host_list="..." dampen="5s" \
        op monitor interval="10s"

This means, that the host is pinged 5 attempts (default), then 10
seconds pause, then another 5 pings , then again 10 seconds pause.

Thus, I would think that if pinging fails (5 of 5 fails), then this is
an "error", but failvoer happens 5 seconds later (dampen). Is this
correct? If yes, then it would make more sense to adapt the examples and
increase the dampen value to cover at least 2 failed ping attempts (5*2s
+ 10s + 5*2s = 30s) or shorten the attempts and interval, e.g.:
attempts=1, interval=2s, dampen=5.

If I am completely wrong, what behavior is really caused by "dampen"?

Thanks
Klaus




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