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Matthew Petach wrote:
<blockquote cite="mid:312187.16786.qm@web31815.mail.mud.yahoo.com"
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<pre wrap="">From: Mustafa <a class="moz-txt-link-rfc2396E" href="mailto:maelhady@eventumsolutions.com"><maelhady@eventumsolutions.com></a>
To: <a class="moz-txt-link-abbreviated" href="mailto:mrtg@lists.oetiker.ch">mrtg@lists.oetiker.ch</a>
Sent: Thu, December 24, 2009 11:45:03 AM
Subject: [mrtg] MRTG exact sampling interval
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<pre wrap="">Dear all,
Please I have a question, in the MRTG .log files
there are 5 columns:
1-
the first one is the time
stamp in UTC
2-
the second one is the average
incoming transfer rate in bytes per second. This is valid for the time between
the UTC of the current line and the UTC of the previous line
3-
the third column is same as the
second but outgoing.
4-
The fourth column is the maximum
incoming transfer rate in bytes per second for the current interval. This is
calculated from all the updates which have occurred in the current interval.
5-
The fifth is the same as the
fourth one but outgoing.
So that means that there is some sampling time that is less than the
specified interval in the "mrtg.cfg" file to be able to detect the
maximum. For example, I have adjusted the interval to be 5 minutes and I got
values in the .log file as the following:
1251871200 124890 463933 204720
497123
1251864000 124836
464014 188781 500925
1251856800 153102
478951 705564 892407
1251849600 129210
466166 185505 515786
As the second column is the average over 5 minutes, and the 4th >column values is much greater than maximum values, so my question is exactly: what is the minimum interval that the MRTG can detect
a certain maximum throughput within it?
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The minimum interval is 5 minutes for detecting throughput.
The section of the config file you have there shows data aggregated up into 2 hour
intervals (note there are 7200 seconds between each line). Thus, column 2 is showing
the average *over two hours*, while column 4 is showing *the highest 5 minute value
recorded during that two hour interval*. That's why the numbers are so different.
If you look at the first 600 lines of the config file, you'll note those are the 5 minute data
samples, and there, columns 2 and column 4 will be almost equal. As the data gets
averaged more and more in subsequent sections of the file, the difference between
the average and peak values generally gets larger.
Hope this helps clarify what you're seeing. :)
Matt
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<pre wrap="">Thanks a lot for your patience and your support, I really appreciate that.
Best Regards,
MUSTAFA A. ABDEL
HADY
Network Engineer
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<br>
To further explain some of this, you are using MRTG in it's native
logging form and not using rrd databases. Because of the way MRTG is
programmed when using native logging and rateup, it does heavily depend
on a 5 minute polling interval. You need to try to poll every 5
minutes to get accurate data and averaging from your devices.<br>
<br>
When you convert to rrd databases, you can poll more often and the
front end(I recommend routers2.cgi) can be fine tuned. But the basis
of all development was built around the 5 minute polling interval, so
unless you have a real serious desire to poll more often, don't. And
the cpu load in rrd mode is way less than using the native logging
within MRTG.<br>
<br>
Lyle Giese<br>
LCR Computer Services, Inc.<br>
<br>
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