[rrd-users] newbie rrd question - probably a very old issue

[Tobias Oetiker]

Dan,

> Sounds like this is in dire need of a FAQ! :)

yes, unfortunately eveyone seems to come from a diffferent angle
 ... but once you got it down, it would be great if you could write
up what you understood ...

> so why does rrd dump and rrd fetch show different results?
> I'll check the "--resolution" option before continuing that question.

rrdtool dump shows the whole rrd file

rrdtool fetch picks one RRA and shows you the data from that RRA

cheers
tobi

> and I could swear I "fixed" this problem with a simple modification to the RRA
> definition.
> I'm almost positive it had something to do with "ABS", but that was 5 years
> ago.


>
>
> > From: Tobias Oetiker <tobi at oetiker.ch>
> > To: Dan Gahlinger <dgahling at hotmail.com>
> > CC: jfesler at gigo.com, rrd-users at lists.oetiker.ch
> > Subject: Re: [rrd-users] newbie rrd question - probably a very old issue
> > Date: Sat, 1 Sep 2007 20:49:26 +0200 (CEST)
> >
> > Dan,
> >
> > note that rrdfetch is NOT consolidating anything, it shows you what
> > is stored in the rrd ... if you want to see what is actually
> > stored, use rrdtool dump ...
> >
> > you may also want to read through the mailinglist archives, since
> > we get someone like you every few months how needs many days of
> > patient explaining until he understand why rrdtool is designed the
> > way it is designed and why it works the way it works, and why this
> > is the right thing todo ... (it has been like this for the last 8
> > years actually and tousands have used and understood the logic) ...
> > you will get there ...
> >
> > cheers
> > tobi
> >
> >
> > >
> > > that's not exactly what I want.
> > >
> > > to be honest, I'd be happy if rrd did one simple thing (or two depending
> > on
> > > your point of view).
> > >
> > > I'd recommend the "min" and "max" of the average function be done a bit
> > > differently.
> > > for an average graph, the "maximum" (shown at the bottom) should always be
> > > kept,
> > > and the "minimum" should always be kept
> > >
> > > also the points for those on the graph should always be kept, even if it
> > means
> > > the verticals in the graph are stretched a bit.
> > >
> > > the graph doesnt have to show ever portion of the scale either. by this I
> > mean
> > > if there are no values between 10 and 40, you dont need to show the
> > portions
> > > from 11-39 essentially
> > > as long as the maximum, minimum and average are represented properly
> > >
> > > it should be simple enough to keep track of the minimum and maximum over
> > time.
> > > my logic:
> > > if you have a spike of 100 one day and that is you maximum, then a week or
> > a
> > > month or a year later, if that is still your maximum, then it is always
> > your
> > > maximum, and the spike should be shown
> > > today it should be the max, tomorrow it should be the max, and until a
> > higher
> > > value occurs, it should always be the max, same with minimum, if we got a
> > > zero, that will always be the minimum. and the overall average should be
> > the
> > > average between those two values.
> > >
> > > otherwise the data is incorrect and quickly becomes meaningless.
> > > yesterday it spiked to 90, but today it shows the max is only 30, so did
> > it
> > > spike? not according to the graph it didnt.
> > >
> > > and I still dont understand why the command line (rrdfetch) is
> > consolidating,
> > > it has no graphing limitations
> > >
> > > I don't know a better way to do it.
> > > Dan.
> > > > From: Jason Fesler <jfesler at gigo.com>
> > > > To: Dan Gahlinger <dgahling at hotmail.com>
> > > > CC: tobi at oetiker.ch, rrd-users at lists.oetiker.ch
> > > > Subject: Re: [rrd-users] newbie rrd question - probably a very old issue
> > > > Date: Sat, 1 Sep 2007 10:09:32 -0700 (PDT)
> > > >
> > > > Based on a side conversation with Dan, this is what I'm understanding:
> > > >
> > > > RRD will graph exactly one consolidated point in time, if there are more
> > > > points than pixels on the X axis.  Dan wants *all* value points
> > represented,
> > > > not consolidated.  RRD has no option to do that.
> > > >
> > > > I'm thinking that *maybe* it can be faked, with some stacked graphs or
> > > > something, *if* MIN and MAX were also included in the rrd file; do a
> > fill
> > > > between min and max.
> > > >
> > > > But it isn't going to happen with a single graph statement, and I'm
> > having
> > > > problems figuring out how to sanely show min/average/max if desired. :-)
> > > >
> > >
> > > _________________________________________________________________
> > > Show Your Messenger Buddies How You Really Feel
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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
>
> _________________________________________________________________
> Kick back and relax with hot games and cool activities at the Messenger Caf??
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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