[mrtg] Re: WithPeak in Daily Graphs - Is daily a valid option?

[Paul C. Williamson]

You've got the basic idea, but you're missing the point.  

The peak that is stored is the actual 5 minute maximum for that 
period (30 minutes, 2 hours, 1 day).  Putting WithPeak on the daily 
is redundant, as no "averaging" comes into play until the data gets 
consolidated from 5 minutes to 30 minutes.

IOW, the WithPeak value for any of the stored 30 minute periods is one 
of 6 values (at 5, 10, 15, 20, 25, 30) and then that value is stored along with 
the 30 minute average.  That's how it works for .log files.  I haven't quite 
figured out how it does that for when you use RRDTool as the backend.

Paul

>>> Glenn Forbes Fleming Larratt <glratt at rice.edu> 01/31/02 08:03AM >>>

Off the cuff, my understanding of it is this:

	- MRTG gets a value periodically (every five minutes by default);

	- MRTG keeps a database (again, by default) of:

		- some number of 5-minute sampling values;
		- some number of 30-minute average values;
		- some number of 2-hour average values;
		- some number of 1-day average values;

	- MRTG calculates the average values as:

                (sum of sampled values)
                    ------------
               (number of sampled values)

	, but it also keeps the maximum sampled value (N.B. there are four
	values throught an MRTG logfile, not two - see also doc of logfile
	format);

	- it seems to me, that with a maximum granularity of the sampling
	interval, the added value of graphing a maximum value is somewhere
	between small and none. It would also be misleading, tending to
	imply greater sample granularity than actually is the case. I
	would bet that it's a deliberate MRTG design choice not to graph
	the maximum values on the Daily graph.

		-g







On Wed, 30 Jan 2002, Cliff wrote:

> Hi folks
>
> The MRTG Docs seem to indicate that WithPeak[_]
> doesn't apply to the daily graph. Just the y,m,w graphs.
>
> However, I find y,m,w,d in the WithPeak statements that
> I find in example configs. WithPeak[_]: y,m,w,d
> is even in the squid config that I got from the squid
> website. Are these references to the daily graph
> really in error or perhaps I have something else askew?
>
> Thanks!
>
>
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				Glenn Forbes Fleming Larratt
				Rice University Network Management
				glratt at rice.edu 


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