RE: What does 95th %tile mean?

[woods () weird com (Greg A. Woods)]

[ On Friday, April 20, 2001 at 00:52:39 (-0400), Charles Sprickman wrote: ]
> Subject: RE: What does 95th %tile mean?
>
> On Thu, 19 Apr 2001, Greg A. Woods wrote:
>
> > Neither MRTG nor Cricket (nor anything with RRDtool or anything similar
> > underlying it), in their standard released form, are truly suitable for
> > accounting purposes since they both can introduce additional averaging
> > errors.  You need to keep all of the original sample data.
>
> This actually works pretty well:
>
> http://www.seanadams.com/95/

If you read that page carefully you'll note that he's using a modified
version of MRTG that doesn't average its samples.  As it says:

   This is a patch to add 95th percentile metering to MRTG. This is not as
   simple a feature as one might think. MRTG normally saves only one day
   worth of 5-minute samples. It is not possible to accurately calculate the
   95th percentile without having all of the samples for a one month period.
   In order to calculate the 95th percentile for a 30-day period, it is
   necessary to save an entire 30 days worth of the 5-minute samples.

MRTG does not do that by default, nor does Cricket, nor will any tool
using RRDtool as an underlying database.

> There was a very similar discussion just weeks ago on the datacenter
> mailinglist as well, you all might want to peek at the archives...

Perhaps you should look again at who posted to that discussion....  :-)

-- 
                                                        Greg A. Woods

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