[mrtg] migrating MRTG

Alex van den Bogaerdt alex at vandenbogaerdt.nl
Tue Jul 22 16:12:23 CEST 2014

----- Original Message ----- 
From: "Ian Diddams" <ian.diddams at issolutions.co.uk>
To: "'Jay Hennigan'" <jay at west.net>; <mrtg at lists.oetiker.ch>
Sent: Tuesday, July 22, 2014 11:07 AM
Subject: Re: [mrtg] migrating MRTG

> Thanks for that Jay.
>>Assuming classic MRTG, most likely just wait.
> Something is clearly not correct because this has been running for over a 
> week now without any history showing n the graphs.

Is the old server still running?  If so, do the following.  Do a couple of 
iterations and script it so that you can do this excercise fast, inbetween 
two MRTG runs.

Wait some time for comments on this email, and test the procedure well, as 
it has been years ago since I performed this action. Things may have 
changed, including my memory.

1: run mrtg once on the old server, simultaneously with the new server.
This is important, doing this will sync the 2 files' timestamps.
The goal is to have lines 3 and beyond look the same, except for the actual 

2: find the line where the old server still had data
3: generate a new file from two parts:
3a: the new file, upto but not including the line found in (1)
3b: the old file, from the line found in (1) and beyond (= older)

Once you are confident that you did steps 1..3 right and you end up with a 
valid log file:
4: replace the log file on the new server with the one you just created
5: delete the graphs
6: wait until MRTG runs again, and look at the newly created images

It goes without saying that you should make copies of your files before 
screwing up, so that you can revert this action and try again.


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