[rrd-users] absolute and relative graphing of the same value

Karl Fischer rrd-users at ficos.de
Tue Jul 8 18:13:58 CEST 2008

Dear all,

I'm looking for a way to display a value in two ways without recording it twice:

Lets say I'm monitoring a typical GAUGE value like diskspace or temperature.

Now I want do display the temperature as an absolute value (=> GAUGE => 25C) *and*
I want to display (in another grapgh) the change rate (eg. +3C/h), which would
be a typical DERIVE application ...

I tried to use GAUGE and operate with rpn PREV, but since the temporary step-size
varys when graphing, I wasn't very lucky in calculating the right numbers ...

Here's the diskspace example - this doesn't always do what I want ...

--title=Used Disk Space - delta in Bytes/h

It seems to have some erratic behavior when changing the start/end time of the
graph and therefore the scale ...

Any hints for me?


- Karl

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