Nagios 'Out Of Memory' Problems

[Marc Powell]

> -----Original Message-----
> From: nagios-users-admin at lists.sourceforge.net [mailto:nagios-users-
> admin at lists.sourceforge.net] On Behalf Of Armistead, Raffy
> Sent: Thursday, March 23, 2006 12:23 PM
> To: nagios-users at lists.sourceforge.net
> Subject: [Nagios-users] Nagios 'Out Of Memory' Problems
> 
> I have a problem with my Nagios server constantly crashing. It keeps
> outputting on the screen Out of Memory errors which causes loss of
access
> to the server. I can ping the box but I cannot SSH or web into it to
view
> any information. This has been happening increasingly more lately. Now
it
> is about every 2-3 days that this is occurring. We have been adding
more
> and more devices to the servers and this problem has been increasing
as
> this occurs. This is how I have it set up.
> 
> 
> 
> I have a Main Nagios server that is running the latest 2.0 (stable)
Nagios
> release. It is monitoring about 6800 devices but it is not actively
> checking the devices. Its main role is to provide a web interface and
> receive passive polls from three other servers which do the polling.
The
> main server also does email notifications when a device goes down. The
> server sends about 30-40 emails a day. I am using NSCA 2.5 between the
> server and the client Nagios servers. I am only monitoring one service
for
> each device which is either TCP or ping depending on the device.
Mostly
> all devices are monitored with TCP (roughly 6000). The rest are
monitored
> with ping. The individual servers are pretty evenly spread with the
number
> of devices. They are about 2000-2500 each. 
> 
> Can someone please help me in resolving this problem? Thanks

Have you determined what process is using the memory? One of the first
steps you should take is to set appropriate ulimits for memory
utilization for that user so that it doesn't bring down the server. I
would configure nagios to monitor memory on that server then use top or
ps to identify the process(es) using the allocated memory when memory
utilization is high. That will provide better direction for
troubleshooting rather than simply that the machine is crashing due to
memory exhaustion. The nagios deamon itself isn't going to be using a
lot of RAM (10M on my box with 3400 passive services).

My somewhat unfounded guess is that perhaps nagios isn't reaping the
results from NSCA frequently enough so you're having a backlog of ncsa
processes. Each process uses just a little memory but if you have
thousands of them then it adds up. I've personally experienced this on a
machine that was experiencing disk problems. If this is the case, beyond
a hardware problem or capacity issue, I'd verify that your
command_check_interval is set to -1 to make sure that nagios is checking
the external command file as quickly as it can.

--
Marc 


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