[Nagiosplug-devel] New rrdtool feature and Nagios plugin?

[Stanley Hopcroft]

Dear Sir,

I am writing to thank you for your letter and say,

On Mon, Jan 03, 2005 at 09:58:51AM -0800, Alf Wachsmann wrote:
> Has someone already thought about how to make use of the new rrdtool
> feature of "Aberrant Behavior Detection with Holt-Winters Forecasting"
> within the Nagios framework?

Yep. 

> 
> The problem is that a probe (check_XYZ) itself cannot decide anymore
> whether a measurement is OK, WARNING or CRITICAL. It is up to rrdtool
> to correlate a new measurment with older ones and then decide whether
> this is OK or not.
>

The setup I have adopted (and didn't go far with) to monitor switch CPU 
solution is to divide the task into 

1 a synchronous data collector (poller) scheduled by cron that gets the 
measurements and updates the (dev branch but quite stable) HW rrd.

2 the plugin that checks whether or not the current measurement (ie the 
last one in the rrd) is within the confidence interval of the HW 
consolidation function (ie HW +/- 2 * something I can't remember now) 
and acts accordingly (In other words, the plugin reads the last values 
from the HW rrd and examines them).

The problem I found is being sure about the periodicity of the data 
sources. We have simply two many aberrations for this technique to be 
very useful, although for things that aren't subject to inexplicable 
surges (CPU temp, Data centre environmentals) it may work better.

In any case, having the graphs of the HW predictions (ie max and min 
lower bounds is very useful), even if not so useful for generating 
alerts.

I think others have used Cacti with HW and had that alert them (Nag 
passive service check results) of violations in link utilisation.

Yours sincerely.
 

-- 
Stanley Hopcroft

Network specialist, IT Infrastructure
IP Australia
Ph: (02) 6283 3189  Fax: (02) 6281 1353
PO Box 200 Woden  ACT 2606
http://www.ipaustralia.gov.au
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