[mrtg] Re: Maximal 5 Minute Incoming Bits Per Second

Jay Hennigan jay at west.net
Sat Apr 15 00:09:27 MEST 2000

On Fri, 14 Apr 2000, Shier, Jon wrote:

> I tried to use the WithPeak[_]ymwd, but it does not show up on the 5 minute
> graph. Only the week month and year. Also I have RunAasDaemon:Yes and
> Intervel:5 , but when I run the kickmtrg.bat it does not show what the other
> colors mean. Did I do the with peak right?

Yes, you did it right.  

It doesn't show on the daily graph because they already show the most 
granular detail that MRTG has captured, five minutes.  

Here's what WithPeak[_] does:

MRTG by default uses average values, and as the interval gets longer the
time between averages is lengthened as well.  This keeps the size of the 
logfiles smaller, as otherwise there would be samples every five minutes
going back for over a year.  

So, on the weekly graph the samples are averaged over 30 minutes.  The 
five minute samples for the daily graph are skipped in such a way that 
the change between every sixth sample (30 minutes) is taken and plotted.
Similarly, the monthly graphs use a sample every two hours, and the yearly 
ones every day.  After the five-minute samples age off of the daily graph, 
they are purged from the logs.  After the 30-minute samples age off of the 
weekly graph, they are purged from the logs, and so on.

But, this does not give an accurate representation of "bursty" traffic.

Looking at a yearly graph of traffic averaged over a day will give the 
impression that the traffic flows steadily throughout the day which is
rarely the case.  For example a stockbroker might show a daily traffic 
average which is quite low as the traffic occurs during the trading day

WithPeak[_] causes the highest of the five-minute samples during each 
averaged period (30 minutes, 2 hours, or one day) to also be graphed. 

As the daily graph already shows the traffic with five-minute granularity
and MRTG has no knowledge of peak traffic occuring within an interval of
less than five minutes, enabling the WithPeak[_] option does nothing to 
the daily graph.

Jay Hennigan  -  Network Administration  -  jay at west.net 
NetLojix Communications, Inc.  NASDAQ: NETX  -  http://www.netlojix.com/
WestNet:  Connecting you to the planet.  805 884-6323 

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