[rrd-users] DST ABSOLUTE does not work as expected

[Tobias Oetiker]

Today Stefan Wernli wrote:

> I'm reading a value minutes of sunshine in the past 10 minutes, which can vary between 0 and 10 and gets read every 10 minutes.
> So I created an rrd with a DST ABSOLUTE, because the source always starts at 0 after each period, expecting the value in the RRD to be like
> 10,20,30,40,50,60 for a full hour of sunshine.
>  
> Data reading is fine:
>  
> ds[sunshine].index = 1 ds[sunshine].type = "ABSOLUTE" ds[sunshine].minimal_heartbeat = 1200 ds[sunshine].min = 0.0000000000e+00 ds[sunshine].max =
> 1.0000000000e+10 ds[sunshine].last_ds = "10" ds[sunshine].value = 0.0000000000e+00 ds[sunshine].unknown_sec = 0
>  
> But in the rrd itself I get weird values:
>  
> <!-- 2015-03-28 08:50:00 CET / 1427529000 --> <row><v>1.6666666667e-02</v></row> <!-- 2015-03-28 09:00:00 CET / 1427529600 -->
> <row><v>1.6666666667e-02</v></row> <!-- 2015-03-28 09:10:00 CET / 1427530200 --> <row><v>1.6666666667e-02</v></row>
>  
> (1.666e-02 is 1/60 btw.)
>  
>  
> What point am I missing?

rrdtool always deals with rates ... so if your input is minutes of
sunshine in 10 minute interval, I would log that value times 60.

If you then want to see sunshine per hour, you simply multiply the
number stored by 3600

cheers
tobi
>
>

-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
www.oetiker.ch tobi at oetiker.ch +41 62 775 9902