[rrd-users] Re: How to save and graph NON-averages

BAARDA, Don don.baarda at baesystems.com
Tue Sep 26 00:24:27 MEST 2000


> -----Original Message-----
> From:	Alex van den Bogaerdt [SMTP:alex at slot.hollandcasino.nl]
> Sent:	Tuesday, September 26, 2000 7:47 AM
> To:	Sam.Howard at trcinc.com
> Cc:	rrd-users at list.ee.ethz.ch
> Subject:	[rrd-users] Re: How to save and graph NON-averages
> Sam Howard wrote:
> > I notice that if I reduce the steptime, to anything other than 3600 or
> 7200,
> > that I get time fluctuations...
> You should get problems with 7200.  Everything under 3600, provided that
> 3600 modulo time step is zero, is okay.
> > I hate to waste so many records (24 per day) just to work around this...
> Just don't look at it as wasting space.  If you have a good reason to
> do so, do so.
> However, for this particular purpose you can say *you* are wasting space
> if *you* choose to use 3600 seconds time steps.  I guess you're only
> interested in the yearly archive and therefore want only update once
> every day.  Do this at 00:00 UTC and there's no problem.

	AFAIK, the "time" used in rrd is just an integer (standard Unix time
type) that is not used in any special way. This (should) mean that you can
use any scaled "time" type as long as you are consistent. For example, in
your case you could use a count of the number of days since your preferred
start date, and increment the "time" by one each day. This would allow you
to enter a single sample per day with no "normalising" and accumulate on day
boundaries of your choice (by picking your preferred start date).

	However, any date parsing features would not know about your special
"timescale", and any graphs produced would have strange dates on the bottom
of them. You would need to take this into account.

	WARNING: I vaguely recall that someone posted that rrd has problems
with dates before some time after 1970. I don't know why this would be the
case, but if true, you would probably have to add some starting offset to
your "timescale" when using this technique.

	If I am wrong and this is not possible, please correct me.


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