[mrtg] Re: Ignoring Negative Deltas

[Tobias Oetiker]

Hi Hector,

mrtg assumes that a 32bit counter roll-over occured ... so unless
your counter is larger than 32bit then the spikes should always be
substantial ... and no problem to catch using maxbytes ... have you
actually seen smaller spikes or is this just your intuition ?

another option would be to teach mrtg an option to zero out counter
wraps ...

cheers
tobi


Yesterday Hector Herrera wrote:

> Hi,
>
> I'm monitoring an external device and the output is in the form of an
> ongoing count.  MRTG works great, it calculates the delta from the
> last sample and then shows the values on the graph.
>
> The problem is when the external device resets or reaches the max
> count.  The last sample is a very large number, the new sample is a
> very small value.  MRTG calculates a huge negative delta.  Here is
> where the problem is, those large negative values show up as a large
> positive spike.
>
> Is there someway to tell MRTG to throw away any deltas in the samples
> that are negative?
>
> or, even better,
>
> Is there a way to tell MRTG to use 0 as the last sample if the delta
> is negative?
>
> Using AbsMax and MaxBytes is not an option because the negative spikes
> are sometimes smaller than real spikes we need to see, and if we set
> AbsMax or MaxBytes low enough, then our real data gets thrown out.
>
> Thank you,
>
> --
> Hector
> Pier Programming Services Ltd.
>
> --
> Unsubscribe mailto:mrtg-request at list.ee.ethz.ch?subject=unsubscribe
> Archive     http://lists.ee.ethz.ch/mrtg
> FAQ         http://faq.mrtg.org    Homepage     http://www.mrtg.org
> WebAdmin    http://lists.ee.ethz.ch/lsg2.cgi
>

-- 
ETH Zurich
Tobias Oetiker, IT Support Group D-ITET (ISG.EE)
ETL F24.2, Physikstrasse 3, 8092 Zurich, Switzerland
Phone +41 44 63 25286,  http://people.ee.ethz.ch/oetiker/

--
Unsubscribe mailto:mrtg-request at list.ee.ethz.ch?subject=unsubscribe
Archive     http://lists.ee.ethz.ch/mrtg
FAQ         http://faq.mrtg.org    Homepage     http://www.mrtg.org
WebAdmin    http://lists.ee.ethz.ch/lsg2.cgi