[mrtg] Problem with Negative Numbers

Daniel J McDonald dan.mcdonald at austinenergy.com
Wed Apr 18 18:31:12 CEST 2007

On Wed, 2007-04-18 at 11:52 -0400, Craig Metzer wrote:
> Im trying to poll a satellite modem for Rx Signal Level.  The modem
> returns a negative integer ten times the level (ex. -575 indicates the
> level is -57.5 dBm).  Ive configured a conversion function so I can
> log the value returned by snmpget and compare it to the value in the
> log file.  It appears that MRTG is not recognizing the number as
> negative.

rateup can't deal with negative numbers at all.  rrdtool as a backend
can be used if you re-tune the .rrd so that MIN is appropriate.

you could ditch the conversion code and use a factor[] statement if you
had an rrdtool backend.

If I recall correctly, the command to retune the rrd file is:

rrdtool tune /path/to/target.rrd -i ds0:-900 -i ds1:-900

Daniel J McDonald CCIE # 2495 CISSP # 78281 CNX
<dan.mcdonald at austinenergy.com>

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