[rrd-users] Re: Weird #'s from basic rrdgraph

Clifton Royston cliftonr at lava.net
Sat Mar 17 01:21:36 MET 2001

On Fri, Mar 16, 2001 at 10:22:07PM +0100, Alex van den Bogaerdt wrote:
> So, you have four RRAs: 5 minutes per row and 20 minutes per row,
> averages and maxima.
> RRA0: 5-minute averages: 120,80,100,100
> RRA1: 5-minute maxima:   120,80,100,100
> RRA2: 20-minute averages: 100
> RRA3: 20-minute maxima:   120
> If you select the wrong RRA, you are selecting the maximum of the
> averages and are thus getting 100, not 120.

I'm not sure this entirely accounts for it; I was just looking at a
similar issue yesterday, which I haven't found the reason for yet.  

In the case I was looking at, if I picked a *narrower* time window
(making sure it was aligned exactly on the width of the MAX RRA, 2
hours) and queried for the MAX, I got a large MAX value (94.5%.) If I
picked a wider time window which was a strict superset (included) of
the narrower time window, but which is not necessarily aligned on the
width of the MAX RRA, and queried the same DSes on the same data file,
I got a totally different, and much lower MAX value.

If it makes a difference, I'm using a Perl script which calls rrdgraph
using the GPRINT function to get out the data.

Would you expect this result?

  -- Clifton

 Clifton Royston  --  LavaNet Systems Architect --  cliftonr at lava.net
   WWJD?   "JWRTFM!" - Scott Dorsey (kludge)   "JWG" - Eddie Aikau

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