Nagios Support Forum

Hi,

I would like to understand how to monitor a remote linux server CPU usage.

Linux server is an ubuntu instance running on amazon cloud.

Nagios server is also running on amazon cloud.

Right now if i go to

configure wizard,

I see CPU but i can only set threshold for IO/WAIT but not for cpu usage.

I would like to know how can we do this.

Thanks.

RJ

jainwolverine,

have you installed nrpe on your ubuntu machine yet? I'm not sure if your cloud instance has any limitations, but that's the first step to monitoring a linux machine.

http://www.omegaprojex.com/index.php/20 ... on-ubuntu/

regards,

-Yancy

Hi Yancy,

Yes i have installed nrpe on my ubuntu server. I believe its working fine.

I am not able to see under CPU section, cpu load. I can see IO wait.

Please check out the attached screenshot.

Is Load option for CPU load?

thanks.

RJ

Suppose i would like to set the following:

Warning if CPU reaches 15%

Criritcal if CPU reaches 40%

Its a 2 core processor.

What should be the values for load? I see there are three values.

for warning and errors

Thanks.

RJ

Those three values are for the 1,5,15 minutes average of the load respectively.

sorry about my lack of understanding on this

So is this correct?

15, 15, 15 for warning

and

40, 40, 40 for critical.

Thanks.

RJ

Yes, that would work, however its generally better to have the warning and critical values go down as the load duration goes up.

For example, say you have a server, that experiences a transient load spike, like a someone grepping a large file that only lasts a minute and then back to normal. This would cause the 1 minute load to be very high, but since it was a short spurt, the 5 and 15 minute readings are not affected too much by it, so allowing a large spike for a short duration is ok. However, if the CPU Usage continues for a few more minutes, the 5 minute average will reflect a higher average, which means the load has been high for most of the five minute period, which is why setting the 5 minute average threshold to be lower is generally a good idea. The same logic is applied for the 15 minute average.

In summary, a computer under 30% CPU Usage for a 1 minute average does not necessarily mean the CPU is overtaxed, so it shouldn't cause a warning or critical. However, a CPU that is consistently about 30% for 5 or 15 would mean there is a process that is running consistently indicates that there is a problem that should be addressed.

Thanks for this explanation.

We monitoring a node.js server and this sever is based on real time application.

We would like to monitor real time spikes. So basically receive an alert as soon as we see a jump in CPU.

5/15 we dont care much.

so basically do you think is this a good number for the load:

warning (1/5/15)

15 10 5

for critical (1/5/15)

40 30 20

Thanks.

RJ

It really depends on the system and how many CPU's you have.

Generally, for most of my systems, I would say this is what I would use on a 4 CPU system...