[rrd-users] Confusion about VDEF total and graph values

humke arjan.hummel at gmail.com
Thu Oct 13 13:58:55 CEST 2016


I am using rrdtool to store values from my smart meter (electricity and
gas). For the gas part I am a bit confused about what is graphed and shown
as a total for the graph's period of time. 

First, some info about the rrd file I use to store the gas counter values
from my meter:

Here's the code I use to create a graph from this rrd:

The $ variables are defined somewhere else and represent actual color codes
and the rrd file name. 

Here's an example of generated graph:


I was expecting the total value mentioned below the graph to be equal to the
sum of all values in the graph. But as you can see it is not (or I
misinterpret things). The gas counter value uses 3 decimal places and this
counter is in m3 (in the rrdinfo output you only see two decimals because
the last decimal is 0). I would expect the y-axis values to be represented
in 'm' instead of 'u'. When I add all the graph values myself I get to a
total of aprox. 380u m3. This does not match with the presented total of
1.384 m3. 

Likely I am misunderstanding some rrdtool concepts here. Could someone
enlighten me?


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