Threshold for processes

[Marc Powell]

> -----Original Message-----
> From: nagios-users-bounces at lists.sourceforge.net [mailto:nagios-users-
> bounces at lists.sourceforge.net] On Behalf Of Palle L Jensen
> Sent: Monday, February 04, 2008 9:09 AM
> To: nagios-users at lists.sourceforge.net
> Subject: [Nagios-users] Threshold for processes
> 


> 
> When I check the CPU/Ram/Network utilization it shows very low on both
> CPU's (2-5%) and below half of the Ram utilization, and only 1/10th of
the
> swap file. Network traffic is low as well.
> 
> 
> 
> Here is my question:
> 
> 
> 
> If the CPU and Ram is not overloaded, what is the critical part with
> processes? And what is really the maximum processes that can be run,
when
> the CPU show no overload (not even close)? Also is the default
threshold

It is entirely possible to have hundreds, thousands or 10's of thousands
of processes 'running' but in a sleep or otherwise idle state with no
system impact if you have enough memory to support them. The critical
part would be the number of processes ready to run but waiting on
processor time. This is generally indicated by the system's load numbers
but even that is not a hard-and-fast measure. For example, I have a quad
processor system with an average load of around 20. That means that
there are 5 processes per processor running, or waiting to run at any
given time (or waiting to access IO systems). Because this is not a
real-time system, it's a mail scanning machine, the few seconds delay
introduced by the number of processes waiting is acceptable. This
probably wouldn't be acceptable on desktop or other type of more
real-time service but even then, priorities can help a lot to maintain a
high load but an interactively normal system.

> set in Nagios just a general threshold i.e Warning over 200 and
Critical
> over 250 procs. What would make the decision of the Warning/Critical
> threshold?

The defaults seem pretty arbitrary to me. You should set them to be what
you consider normal for the machine and the duties it's performing. For
example, on the mail system above, it is normal and acceptable to have
~360 processes 'running' at any given time. I'd be interested if that
exceeded 450-500ish. On another system, it's normal to have about 80
processes running. I'd be concerned if that exceeded 100.

HTH,

--
Marc



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