question on parallelization

[Josh Larsen, Monitored Security]

If I recall, parallelization only occurs on _service_ checks.  If you force a _host_ down state, you will force Nagios to start doing host checks (remember host checks only get executed when service checks for that host fail), which do not get parallelized (is that a word?).  In other words, ping checks are bad for host checks due to the latency and long timeout which you mention.  I typically use a TCP port check as the host check.  In many instances my host check is actually the same check as the service check -- redundant, but I don't have a need to differentiate.

I'm not exactly sure what you mean by "fake a down state".  In any case make sure you take into account the differences between host checks and service checks.

HTH.


-----Original Message-----
From: Eric Young [mailto:ericryoung at yahoo.com]
Sent: Tuesday, October 22, 2002 1:08 PM
To: nagios-users at lists.sourceforge.net
Subject: [Nagios-users] question on parallelization


I'm using nagios on RH 7.3 with no DB backend stuff.

Perhaps I'm confused on something but I don't seem to
be getting any parallelization (yes, it IS turned on).
 I have about 140 hosts for which I have defined a
service that basically runs check_ping every 60
seconds.  Therefore, I would expect to have multiple
pings running on my machine at once (maybe 2 at a
time?)  While I haven't checked, during normal
operation, I seem to get great response time on these.

I have 135 or so of the nodes with a common parent
(ie: a router).  When I 'fake' a down state for the
router I do get a notify as I expect and the child
nodes do get marked off slowly.  Some other nodes that
actually should go down when I do this don't notify
for quite a while.  It LOOKS like there is only 1 ping
running at a time on my machine (though I have from
90-130 nagios processes running).  Since each ping has
a timeout that takes a bit, detection of other down
hosts is very slow.

The final question is, if things are parallelized and
my pings are piling up (I'll sometimes see more than
30 minute old service checks in the process queue on
the web interface) then why doesn't nagios launch more
pings?  I have read the 'scheduling' documentation and
it doesn't seem to answer this question.

Have I given you enough information?  Am I missing something?

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