[Xymon] Discarding Powershell client CPU negative values

[Scot Kreienkamp]

Excellent point Norbert, one that I had considered as well.  I chose to do what I did because otherwise the graph was unreadable and unuseable.  I would rather have small parts incorrect and still be able to use the graph to visualize the overall history.  I would much rather the source be corrected.

As an alternative, the RRD for load could (and arguably should, since load cannot be negative) be set to reject negative numbers without any harm to the accuracy.  That was my original goal, but I was unable to quickly figure out a way to do so.


Scot Kreienkamp  | Senior Systems Engineer | La-Z-Boy Corporate
One La-Z-Boy Drive | Monroe, Michigan 48162 | Office: 734-384-6403 | | Mobile: 7349151444 | Email: Scot.Kreienkamp at la-z-boy.com
From: Xymon [mailto:xymon-bounces at xymon.com] On Behalf Of Norbert Kriegenburg
Sent: Wednesday, December 14, 2016 10:47 AM
To: xymon at xymon.com
Subject: Re: [Xymon] Discarding Powershell client CPU negative values


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).

Norbert


[Inactive hide details for Scot Kreienkamp ---14/12/2016 16:22:26---Hi list, I have a powershell client that is occasionally rep]Scot Kreienkamp ---14/12/2016 16:22:26---Hi list, I have a powershell client that is occasionally reporting negative values for CPU usage. S

From: Scot Kreienkamp <Scot.Kreienkamp at la-z-boy.com<mailto:Scot.Kreienkamp at la-z-boy.com>>
To: "xymon at xymon.com<mailto:xymon at xymon.com>" <xymon at xymon.com<mailto: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<mailto: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:

36,37c36
< 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:
[la]
TITLE CPU Load
YAXIS Load
DEF:avg=la.rrd:la:AVERAGE
CDEF:la_min0=avg,100,/
CDEF:la=la_min0,0,1000,LIMIT
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 | | • 7349151444 | • Scot.Kreienkamp at la-z-boy.com<mailto:%7BE-mail%7D>
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