[rrd-users] peak after NaN?

[Tobias Oetiker]

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
>
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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