Alerting based on past-to-current trends?

[Jim Avery]

On 10 December 2010 18:43, Rick Carter <Rick.Carter at umich.edu> wrote:
> Hi Jim,
>
> I'm wondering if load average would get you where you want to be, as in a lot of cases, a CPU busy might not be a big deal unless the run queue is growing.
>
> My nagios-fu isn't good enough to tell you how to get that, but when I saw your message, I thought right away of the linux/unix:
>
> $ uptime
> 13:41  up 2 days, 18:11, 2 users, load averages: 0.31 0.25 0.24
>
> Where the 2nd load average is the 5-minute one.
>
> - Rick

Good point Rick,

there is a check_load plugin, and you could indeed set appropriate
thresholds to make it concentrate on the 15-minute value rather than
the 5-minute or 1-minute values.

As to what 'load' actually means I'm not 100% sure.  I've read
http://www.teamquest.com/resources/gunther/display/5/index.htm a few
times, and think it helps a bit!  I even bought Gunther's book
"Guerilla Capacity Planning" but confess I haven't read anywhere near
all of it.

I seem to recall reading somewhere that as a general rule of thumb if
load is > 2 * the number of cpus, it's probably affecting performance.
 Certainly on my own Nagios server with 4 CPUs I find it's struggling
whenever load is consistently > 10.

Cheers,

Jim

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