[rrd-users] Re: 0 values in rra

Alex van den Bogaerdt alex at ergens.op.HET.NET
Wed May 1 00:50:32 MEST 2002

Vlad Dimitriu wrote:

> 	/usr/local/bin/rrdtool \\
>         create \\
>         --start N --step 300 \\
>         /somepath/db/mdm??.rrd \\
>        DS:lrx:ABSOLUTE:600:-100:200 \\
>        DS:ltx:ABSOLUTE:600:-100:200 \\
>        RRA:AVERAGE:0.5:1:105120

I see two question marks in the filename.  I assume these are
special characters my system cannot handle.  Perhaps RRDtool has
a problem with it.  I doubt it is a problem, this is just to be sure.
Try with a filename without "difficult" characters, such as "test.rrd"

> at some moment, A crontab script colects the data with snmp and updates
> the database :
> /usr/local/bin/rrdtool 
> update 
> /somepath/db/mdm??.rrd 
> -t lrx:ltx 
> N:$FRX1[1]:$FTX1[1]
> the values are corectly provided but :

Are the values correct?  How do you know *for sure* ?

> rrdtool fetch /somepath/db/mdm??.rrd AVERAGE -s -1200 -e +1200

Looks good...

> 1020203400: NaN NaN
> 1020203700: 0.0000000000e+00 0.0000000000e+00
> 1020204000: 0.0000000000e+00 0.0000000000e+00
> 1020204300: NaN NaN

So, RRDtool is reporting it got zeros.  It divided those zeros by 300
and the resulting rate is 0 per second.

> 	Where am I wrong? The two data sets are not counters, just some 
> parameters like the temperature. I could run the update scripts from 
> crontab for days and I get only zero's in mdm??.rrd. Maybe the date of 
> rra creation and the data of the first update may be wrong ?

Temperature and so on does not need to be divided by time.  COUNTER
is a wrong choice as is ABSOLUTE.  The only correct type for temperature
and similar sources is GAUGE.

Even then, using ABSOLUTE here should still show you numbers other
than 0 unless RRDtool receives 0.

Perhaps N:$FRX1[1]:$FTX1[1] is not what you think it is.

 / alex at slot.hollandcasino.nl                  alex at ergens.op.het.net \
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