[rrd-users] Simple questions about RRD

[A Darren Dunham]

On Sun, Dec 06, 2009 at 12:19:36AM +1100, Jean-Yves Avenard wrote:
> 2009/12/5 A Darren Dunham <ddunham at taos.com>:
> >
> > Hopefully that demonstrates the differences pretty well.
> >
> 
> Actually ; looking at the graph ; I can't understand how the MAX is
> actually calculated.
> 
> Looking at:
> http://htpc.avenard.org/power/screen.png
> 
> It shows the maximum as being 2972W ; which is indeed the maximum with
> the actual data at the highest resolution.
> But it's definitely not the maximum of 5 minutes average as the graph
> shows: nothing is over 2200W
> 
> That graph is created with :
> 
> $ret = exec("$RRDTOOL graph $name -l 0 \
> -t '$title' \
> -x $legend \
> --step $res --start e-$start --end $timestamp \
> -w $width -h $height \
> DEF:total=currentcost.rrd:total:AVERAGE DEF:ch2=currentcost.rrd:ch2:AVERAGE \
> DEF:solar=solarprod.rrd:total:AVERAGE DEF:ch1=currentcost.rrd:ch1:AVERAGE \
> DEF:totalmin=currentcost.rrd:total:MIN:reduce=AVERAGE
> DEF:ch2min=currentcost.rrd:ch2:MIN:reduce=AVERAGE \
> DEF:solarmin=solarprod.rrd:total:MIN:reduce=AVERAGE
> DEF:ch1min=currentcost.rrd:ch1:MIN:reduce=AVERAGE \
> DEF:totalmax=currentcost.rrd:total:MAX:reduce=AVERAGE
> DEF:ch2max=currentcost.rrd:ch2:MAX:reduce=AVERAGE \
> DEF:solarmax=solarprod.rrd:total:MAX:reduce=AVERAGE
> DEF:ch1max=currentcost.rrd:ch1:MAX:reduce=AVERAGE \
>     VDEF:ds0max=ch2max,MAXIMUM \
>     VDEF:ds0avg=ch2,AVERAGE \

[snip lots more stuff]

Easiest way for others to help is if it's really easy to reproduce it.
Can you create a minimal RRD create setup (probably don't need all your
production DEFs) and some canned data that shows the issue?  The exact
data that enters the RRD is often the key to what's going on.

-- 
Darren