[rrd-users] peak after NaN?

[Tobias Oetiker]

Today Nuno Gonçalves wrote:

> I didn't understood your explanation.
>
> If MRHB(90s in my rrd) is elapsed then the next sample received will
> be ignored? It cannot be considered for the next period...?

yes, because it is over the maximum periode duration, so the next
sample will establish the start of the new periode ...

> I also didn't figure how that relates to my problem, in witch I get a
> value that cannot be the average of any samples...
>
> I didn't include the proper rrd definition in my previous e-mail, so it is:
>
> rrdtool create "$rrdfile" --step 60 DS:pressure:GAUGE:90:0:1100
> DS:temperature:GAUGE:90:-50:100 DS:humidity:GAUGE:90:0:100 \
>	RRA:AVERAGE:0.5:1:10080 \
> 	RRA:AVERAGE:0.5:60:8760 \
> 	RRA:AVERAGE:0.5:1440:3650 RRA:MAX:0.5:1440:3650 RRA:MIN:0.5:1440:3650

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 ...

the shorter, the better

cheers
tobi

>
> Thanks,
> Nuno
>
> 2009/4/13 Tobias Oetiker <tobi at oetiker.ch>:
> > Today Nuno Gonçalves wrote:
> >
> >> I have a rrdtool database created with:
> >>
> >> >rrdtool create "$rrdfile" --step 60 DS:pressure:GAUGE:90:0:1100 DS:temperature:GAUGE:90:-50:100 DS:humidity:GAUGE:90:0:100
> >>
> >> The samples are entered in 60s steps with:
> >>
> >> >rrdtool update "$rrdfile" N:$P:$T:$H
> >>
> >> After a computer restart, that made 2 missed samples, I noticed a
> >> down-peak on the graph and did a rrdtool fetch to check:
> >>
> >> >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
> >>
> >> The same samples are also recorded to a text file to I could confirm
> >> that it was not a sensor problem, the values feed to rrdtool where
> >> between 996.1-995.8.
> >>
> >> In >1239617880: 9.8159131106e+02 1.9585499172e+01 4.9668510483e+01,
> >> where did come the 981.59?
> >
> > Hi Nuno,
> >
> > the first sample after an interval longer than MRHB is used simply
> > to re-enable data entry. The reason for this is, that rrdtool
> > associates a 'timespan' with each update, and if the time since the
> > last update is longer the mrhb then it can't and will thus ignore
> > the value of the update.
> >
> > hth
> > tobi
> >
> >>
> >> Thanks,
> >> Nuno
> >>
> >> rrdtool 1.2.30
> >>
> >> _______________________________________________
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> >> 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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>

-- 
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