high latency

[Andreas Ericsson]

On 12/03/2010 08:14 PM, Frost, Mark {PBC} wrote:
> 
> Can the use of dependencies also be the cause of increased latencies?
> 

If they're very deep, it's possible. Otherwise it really shouldn't matter
all that much. It will ofcourse add *some* load, but it shouldn't be enough
to cause latency.

> I too struggle with them and I'm running on lightly-loaded physical hardware.
> We have 2 servers doing the checks sending back to a central server.  Both
> distributed nodes use ocsp/ochp, but they do nothing more than append results
> to a file (i.e. it exits quickly).  Results are handled outside of Nagios.
> 

Try getting rid of the oc[sh]p commands and use Merlin or google for "pnsca" or
"persistent nsca". There's one available from op5's repositories that may or may
not work, and there's one from somewhere else that they're apparently using to
great effect.

Even if it exits quickly, it's still executed serially, so checking halts a
small period of time for each and every check that runs.

> What's odd is that distserver 1 and distserver 2 are configured the same
> 
> distserver1:
> Hosts Checked       675
> Services Checked:  4179
> Active Service Latency:         0.000 / 3.155 / 0.382 sec
> Active Service Execution Time:  0.000 / 60.038 / 0.145 sec
> 
> distserver2:
> Hosts Checked:      261
> Services Checked:  4289
> Active Service Latency:         0.000 / 169.977 / 81.300 sec
> Active Service Execution Time:  0.000 / 15.270 / 0.211 sec
> 
> yet as you can see, distserver2's latency is much higher and always has been.
> I tried turning off EPN yesterday on distserver2 and it had no discernable effect.
> We added 400 new service checks yesterday on distserver2 (just more of the same
> checks we already do but on 26 new hosts) and the latency went from 35 to over 80.
> 

What kind of checks are you running? Some plugins draw a lot of cpu.
Are any of the checks set to run in serial (grep for parallelize_check in your
objects.cache file).

What version of Nagios are you running?

> The checks we do are very different (Windows, Linux, Unix, many are app-centric) so
> it's difficult to compare exactly what runs on distserver1 and distserver2, but given
> the jump that was taken yesterday, I'm wondering if the fact that the type of checks
> on these new hosts are all built on dependencies make me wonder if that doesn't
> have something to do with it.  These hosts (Windows) have a basic check for NRPE
> and all other checks on the host are dependent on the NRPE check succeeding.
> 
> I have to move to all new Nagios servers very soon.  I'm interested in Merlin, but
> given its non-production nature just yet, I'm hesitant to commit and I'm not sure if
> it will help me here.
> 

It's been running at our 400+ customers with very few problems for the past month.
0.9.1, released just yesterday, solves the known issues our customers have
encountered. You might want to take a look at it again. There are some issues on
FreeBSD though (was that you reporting them?). I just recently got a new laptop
with better support for running virtual systems, so I'm downloading a FreeBSD 8.1
install dvd as we speak. Hopefully I'll have those issues sorted out before the
end of the week.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Considering the successes of the wars on alcohol, poverty, drugs and
terror, I think we should give some serious thought to declaring war
on peace.

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