[Xymon] Discarding Powershell client CPU negative values

Norbert Kriegenburg norbert.kriegenburg at de.ibm.com
Wed Dec 14 16:46:59 CET 2016

Hi all,

i had this problem (with different monitors) from time to time as well.
Scots suggestion will do the trick by suppressing the negativ values to be
displayed at the graphs, but has some drawbacks:

Keep in mind that the aggregation of values in rrd takes all numbers from
rrd file into account. That means your wrong negative number will impact
your overall graph also for the positive numbers in the history, and can
lead to a more or less wrong graph (dependend how many and of which values
you have for negatives).
This can result in some kind of very false trends in the longer term
history, and you will not see where this comes from...

That means: better would be to fix the root cause (as always).


From:	Scot Kreienkamp <Scot.Kreienkamp at la-z-boy.com>
To:	"xymon at xymon.com" <xymon at xymon.com>
Date:	14/12/2016 16:22
Subject:	[Xymon] Discarding Powershell client CPU negative values
Sent by:	"Xymon" <xymon-bounces at xymon.com>

Hi list,

I have a powershell client that is occasionally reporting negative values
for CPU usage.  Since that’s not possible I wanted to pass along this easy
modification for load average in the graphs.cfg for any clients that want
to get rid of the negative values on their graphs.  This doesn’t remove
them from the RRD, just discards values below 0 and above 1000 when
generating the graph.  Load cannot be negative so this may be something to
include in the base configuration.

Here’s a diff:

<       CDEF:la_min0=avg,100,/
<       CDEF:la=la_min0,0,1000,LIMIT
>       CDEF:la=avg,100,/

And here’s what my graphs.cfg looks like now:
        TITLE CPU Load
        YAXIS Load
        AREA:la#00CC00:CPU Load Average
        -u 1.0
        GPRINT:la:LAST: \: %5.1lf (cur)
        GPRINT:la:MAX: \: %5.1lf (max)
        GPRINT:la:MIN: \: %5.1lf (min)
        GPRINT:la:AVERAGE: \: %5.1lf (avg)\n

Scot Kreienkamp | Senior Systems Engineer | La-Z-Boy Corporate
One La-Z-Boy Drive | Monroe, Michigan 48162  | ( 734-384-6403 | | )
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