[rrd-users] Sampling at a higher rate than "step"

[Tobias Oetiker]

Wolfgang,

> Is there any detailed documentation about how "calculation" is
> done in this case?
>
> a.) Will the values be averaged ?
> b.) will this allow to get 1min maximum if I create
>      a MAX-RRA on the finest RRA ?


what happens, is that rrdtool will take the exact arival time of
each value into account and integrate the space below the curve
created by these values. When the step time arrives it will store a
value which will create a 'space' below the 'curve' that is
equivalent to the space below the curve build by the individual
updates you provided ...

the curve in this context is very simple and square ... for counters
this is perfect, for gauge type datasources one could argue that a
striaght connection betweenn the gauge values would be better (but
it is not implemented in that way).

everything else is build based on these initial step vales ... aka
MIN, MAX, AVERAGE will all be the same for a 1 step rra.


> BTW: I'm planning to have two redundant pollers feeding
>       the same rrd-files (with a DB-Cluster as a layer between)
>       in a 5min interval ... this will result in two updates
>       per "step". Any comments on this idea are wolcome ;-)

note that you cann not update individual datasources ... you must
always update all of them ...

cheers
tobi

>
>
> > tobi
> >
> >
> > Today Everton da Silva Marques wrote:
> >
> >> Hi,
> >>
> >> Is there any undesired side effect from
> >> feeding rrd archive at a rate higher than
> >> the specified "step"?
> >>
> >> I mean, what if I feed a 300-sec-step
> >> database at 60-sec intervals?
> >>
> >> Please advise.
> >>
> >> Thanks,
> >> Everton
> >>
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> >>
> >>
> >
>
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-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten
http://it.oetiker.ch tobi at oetiker.ch ++41 62 213 9902