[rrd-users] [rrd] Can't I turn off data smoothing for GAUGE?

Tobias Oetiker tobi at oetiker.ch
Thu Aug 19 07:41:57 CEST 2010

Hi Marc,

Yesterday Marc MERLIN wrote:

> On Wed, Aug 18, 2010 at 09:38:20AM -0700, Marc MERLIN wrote:
> > > as for storing arbitrary binary data as time series in rrdtool, it
> > > is all a matter of coming up with a sensible configuration model
> > > and implementation strategy for makeing this work ... if you want
> > > to spend your time on this, I'll be glad to review your plan and
> > > code. And I will also merge your patches if we can agreee on things
> > > ...
> > >
> > > but as you dive into the code you will seee that your project would
> > > require rather fundamental 'work'
> >
> > I had a simple thought this morning: just ignore any value that's been
> > interpolated by cacti and throw it away.
> > An easy way to detect one is that it's very unlikely that it'll be an
> > integer, so instead of
> Going back to your point, while I don't need this myself anymore (although I
> just see another message apparently asking for the same thing), how about
> this:
> - make a new DATA type that is similar to GAUGE without smoothing

yes the separate datatype approach would be 'the thing todo' note
though rrdtool is not 'smoothing' anything, what happens, is that
rrdtool re-samples your input at the configured step frequency (so
if you put in your data at exactly the step-points, no re-sampling
will happen) for thing you do not need to change rrdtool, just fix
your input. If you do want to be able to have some of the data
re-sampled and some not inside the same rrd, code changes would be
required, as you would have to adopt some sort of 'keep the last
update that has arrived within the sampling interval and mark it
valid for the whole interval'- aproach.

At the next level you might also want to add a special RRA type
which does not do consolidation ... maybe the LAST type might
double as that ...

And thirdly you would have to change storage type of data inside
rrdtool to 'long long (64bit integer)'  from the normal double
since double would prevent your bitfield input from working when
you use all the bits ...

Then the code in rrd_graph would have to be adapted to unserstand
the new DS and RRA types


> or
> - add a rrdtool create flag for GAUGE where it's marked as no smoothing
> I haven't looked at the code and can't comment on how difficult either is,
> but I can think of several legitate uses for GAUGE where smoothing would not
> be ok (not counting my bitfield thing, which is admittedly mabye a bit
> beyond what rrdtool fields were originally meant for, even if it happens to
> work great ;) ).

as I said ... I'll be glad to review any patches ...


> Marc

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900

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