[rrd-users] RRA/RRD tuning

Christoph Anton Mitterer calestyo at scientia.net
Sun Aug 12 16:31:27 CEST 2012

Hi Tobi.

Thanks for your replies :)

On Sun, 2012-08-12 at 09:07 +0200, Tobias Oetiker wrote:
> > As far as I understand, less RRAs should mean faster updates, right?
> yes
So that also means, from just focusing on the update time (and ignoring
space and graphing)... the best would be to have _just one_ (very
detailed) RRA, going with the highest step resolution over the full time
period.... even if it's 200 years...

In other words,... the RRAs are solely intended to do the follwwing
a) decrease space for periods more back in time where no high precision
is needed anymore
This should be the only case when the RRA has less resolution than the
one with the highes resolution, _but_ goes further back in time

b) increase graphing time
This should be only the case for those parts of an less detailed RRA,
that is in the same time range as the higher detailed.

As all RRAs always start at the same time range (i.e. now)... it's not
possible to get just (a).

Ok... if all that is correct... I think it would make perhaps sense to
add this somewhere to the documentation, doesn't it?
At least I couldn't directly read out that information from what I've
found :)

> it is smart enoughh ...
Simply awesome! :D

> the biggest win for graphing time would be to integrate support for
> setting the png compression level into rrdtool ... libcairo sets
> this very high, and thus spends considerable time compressing the
> resulting png file ... setting the compression level to 1 should
> give a considerable performance gain ...
Are there any time comparisons between the different formats (I mean PNG
vs. SVG, etc.)?

> I will be glad to integrate your patch
I just had a small glance on the cairo api... but it doesn't seem as if
it would export an interface to set the compression level... so that
would have probably to be implemented there first.

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