[rrd-users] Beginner RRDTool question

Sam Crawford samcrawford at gmail.com
Mon Mar 10 00:47:36 CET 2008


Alex,

Thanks for the advice - you were spot on. Writing U's on every iteration
would require far too much load (there's several hundred thousand RRDs
here), so I've incorporated some simple logic to test to see if a value was
written on the last iteration. If not, then a U is written prior to writing
the actual data. Seems to work well so far...

Thanks again,

Sam


On 09/03/2008, Alex van den Bogaerdt <alex at ergens.op.het.net> wrote:
>
> On Sun, Mar 09, 2008 at 08:09:03PM +0000, Sam Crawford wrote:
> > Evening all,
> >
> > I'm trying to use RRDTool for a network monitoring application I'm
> receiving
> > data from. The application gives me a bytes/sec reading for active hosts
> > every 5 minutes (note: not all hosts, only active ones).
> >
> > My problem is that I might receive a burst of data for one interval and
> then
> > nothing else for a long time. However, I still want the rrd to record
> and
> > graph it. But I can't seem to get this working!
>
>
>
> RRDtool is not about numbers, it's about rates during an interval.
>
> Don't look at just one update. Always look at two consecutive updates.
> You will be asking RRDtool to set a rate, valid for the entire interval
> between the two timestamps.
>
> Howver, if your updates are too far apart (where too far is defined by
> heartbeat) the rate becomes unknown.
>
> Solution for you:
>
> Always update every five minutes. If you did not get a rate from your
> device, update using "U" instead of a number.
>
> HTH
>
> --
> Alex van den Bogaerdt
> http://www.vandenbogaerdt.nl/rrdtool/
>
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> rrd-users at lists.oetiker.ch
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>
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