[rrd-users] Still get nan values from rrdtool graph DEF VDEF

Alex van den Bogaerdt alex at vandenbogaerdt.nl
Fri Jul 4 10:56:50 CEST 2014

> Hello;
> I don't think is suppose to happen.
> FIRST sued in VDEF context is supposed to provide the first non NAN value
> for the selected data stream
> And yet I'm getting ..
> $ rrdtool graph placeholder.png DEF:CPUBusyx=mydata.rrd:CPUBusy:AVERAGE
> VDEF:CPUBusyFirst=CPUBusyx,FIRST  "PRINT:CPUBusyFirst:%18.5lf"
> 0x0
>               -nan

The code returns NaN if there is only NaN available. In that case it also
returns time zero. Please print the time component and look at this.

Retry your example with a specific start and end time, on data which you
know to be known.

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