graphing real values with rrd

Hello Xymon mailing!

I'm facing the following challenge; I would like to graph the actual disk space used instead of the percentage.
One of the reasons I want to do this is because I want to keep track when I last expended my disk etc...

I read the rrd documentation about graphing but I can't get my head around how I can make xymon do it.
Can anybody point me in the right direction? Does the default disk test from bbwin collect the right data for rrd to do this?

Thanks in advance!

Cedric Steenbeke
Dienst Informatica
AZ Nikolaas
Tel: +XX X XXX XX XX