[rrd-users] Holt-Winters - Seasonal value

Lyle Brooks brooks at deseret.com
Thu Mar 11 21:00:47 CET 2010

I'm trying to wrap my brain around the Holt-Winters capabilities
within RRD tool.

The concept of "seasonal period" is what I'm not sure if I understand
and how to translate it into the correct value when defining my RRA.

The data I am tracking has a step value of 5 minutes.  I "think" my
data has a seasonal value of 1 week.  By that I mean, the traffic 
pattern is this Friday's traffic is similar to each previous Friday,
but is not related to the previous day.

So my questions are...

1) What is the appropriate setting for the SEASONAL value when creating
an RRA with HW?

2) If the algorithm detects aberrant behavior based on a previous season,
would it make sense to have more that one previous season's worth of
values to determine what is normal behavior.  In my case, would 4 or 8 weeks
of data be yield more accurate baseline than 1 week of data?   Or am
I mis-understanding how the SEASONAL coefficients are utilized.

I've read some Holt-Winters related documentation and have played around
with the various alpha/beta/period parameters, but I'm not sure I have
a full grasp of these concepts.

Any help would be appreciated.


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