[rrd-users] peak after NaN?

[Nuno Gonçalves]

root at OpenWrt:/home# rrdtool create met.rrd --step 60
DS:pressure:GAUGE:90:0:1100 RRA:AVERAGE:0.5:1:10080
root at OpenWrt:/home# rrdtool update met.rrd N:998
root at OpenWrt:/home# rrdtool update met.rrd N:998
root at OpenWrt:/home# rrdtool update met.rrd N:997
root at OpenWrt:/home# rrdtool update met.rrd N:998
root at OpenWrt:/home# rrdtool update met.rrd N:998
root at OpenWrt:/home# rrdtool update met.rrd N:998
root at OpenWrt:/home# rrdtool fetch met.rrd AVERAGE -s -300
                       pressure

1239669900: nan
1239669960: 9.9704365867e+02
1239670020: nan
1239670080: nan
1239670140: 9.7894216081e+02
1239670200: nan
root at OpenWrt:/home# rrdtool
RRDtool 1.2.30  Copyright 1997-2008 by Tobias Oetiker <tobi at oetiker.ch>


2009/4/13 Tobias Oetiker <tobi at oetiker.ch>:
> Today Nuno Gonçalves wrote:
>
>> 2009/4/13 Tobias Oetiker <tobi at oetiker.ch>:
>> > yes, because it is over the maximum periode duration, so the next
>> > sample will establish the start of the new periode ...
>>
>> I've done some tests and I concluded that the RRA timespan is always
>> between two points that verify TIME%(rrd_step*rra_steps)==0. Is this
>> correct? What will the sample time decide about the periode in this
>> case...?
>
> rrdtool uses the time stamp you suply and then resamples the data
> ... ignoring 'unknown' time ...
>
>> > from what you tell here I can not see what is going wrong ... best
>> > is, if you write a little demo script to show your problem ...
>>
>> On the rrdtool fetch I provided,
>>
>> >> >> >1239617640: 9.9586069400e+02 1.7373722021e+01 5.6504290012e+01
>> >> >> >1239617700: 9.9586000000e+02 1.7776053280e+01 5.7130494367e+01
>> >> >> >1239617760: nan nan nan
>> >> >> >1239617820: nan nan nan
>> >> >> >1239617880: 9.8159131106e+02 1.9585499172e+01 4.9668510483e+01
>> >> >> >1239617940: 9.9584083364e+02 2.0126658206e+01 5.0490830009e+01
>> >> >> >1239618000: 9.9583079547e+02 2.0435340373e+01 5.1061476218e+01
>>
>> You can see a low-value of 981.59 for the first DS after the NaN time.
>> I didn't entered any value lower than 995.8, so that cannot be a
>> average!
>
> I know that you think you did not ... in order to verify this
> problem, it helps when you provide an example constructed from
> rrdtool create, rrdtool update, rrdtool fetch to demonstrate the
> probem for others to reproduce ...
>
> there was an issue in connection with N: updates and long intervals
> at some point, which may be hitting you if you are not using an
> up-to-date version of rrdtool
>
> cheers
> tobi
>
>>
>> Nuno
>>
>> _______________________________________________
>> rrd-users mailing list
>> rrd-users at lists.oetiker.ch
>> https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
>>
>>
>
> --
> Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
> http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900



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