[mrtg] Re: peaks

[James Overbeck]

Shahira,

Try looking down the list of timestamps in a log file for an MRTG config 
that is run every five minutes but displaced from five minute marks, say 
at 3 minutes past, then 8 minutes past, then 13, and so on. You'll 
notice that the first few timestamps occur exactly when MRTG was run, 
but after the first few they occur at 5 minute marks, at 5,10,15, 20 
minutes past the hour, and so on. The last three digits of each 
timestamp will follow a sequence of 000, 700, 400, 100, 800, 500, 200, 
900, 600, and 300 as you go down.

For the most recent day or so of data after the first few lines in the 
log file, the average columns are created by averaging consecutive 
samples of data, and the maximum column is the maximum of the two in 
each averaged pair. For the first day even though you're already 
sampling at five minute intervals, those samples are averaged and maxed 
to put the data samples at five minute marks. Not sure why, possibly to 
make calculations easier. After the first day or two and during the 
first week or two, I think it switches to 15 or 30 minute steps instead 
of five minute steps. The steps get larger the further back in time you go.

-james


nate wrote:
> Shahira Rasmy said:
> 
>>Dear Friend,
>>
>>I want to add to your question another one concerning the same subject.
>>That's is,the last 2 columns in the MRTG log file expresses the max
>>values.But really i can't understand from where these values are got if
>>the mrtg only averages every 5 minutes and so how it can obtain the max.
>>values between these 5 minutes ??
> 
> 
> MRTG has multiple levels of accuracy:
> 
> 5 minute
> 30 minutes
> 2 hours
> 1 day
> 
> the docs explain this for the 'avgpeak' option(just an example):
> 
> avgpeak
>     There are some ISPs who use the average Peak values to bill their
> customers. Using this option MRTG displays these values for each graph.
> The value is built by averaging the max 5 minute traffic avarage for
> each 'step' shown in the graph. For the Weekly graph this means that it
> builds the average of all 2 hour intervals 5 minute peak values.
> (Confused? Thought so!)
> 
> 
> nate
> 
> 
> 
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