[rrd-users] False positives with aberrant behavior detection

[Mike Schilli]

On Mon, 16 Aug 2010, Tobias Oetiker wrote:

> you may find some inspiration here
> svn://svn.oetiker.ch/rrdtool/trunk/tutorial/lisa2009/rrd-by-example

What would be helpful is a collection of use cases, and explanations on
how to remedy common problems with either too many false positives or
obvious errors that aren't picked up.

"Twiddle the 4 knobs until it looks right" is neither a valued
engineering tradition (at least where I come from) nor a guarantee that
it won't be out-of-whack again tomorrow.

Curious: Since you mention in one of the .tex files that "no one
considers himself clever enough to use it": Are there any applications
in the wild that have been using the feature for a while with satisfying
results? I'd be interested if someone can actually come up with a set of
parameters so that the anomaly in [1] gets detected without false
positives. It's an easy case and should be fast to solve.

As it stands, and with the confusing results I'm getting, I'm wondering
if rrdtool's implementation of Holt-Winters is useful at all, or even
correct.

-- Mike

Mike Schilli
m at perlmeister.com

[1] http://perlmeister.com/tmp/rrdhelp.data