[rrd-users] peak after NaN?

[Nuno Gonçalves]

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...?
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

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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>>
>>
>
> --
> 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