[mrtg] New MRTG install... Run as Daemon and RRD setup?

Arvon Griffiths Arvon.Griffiths at txdot.gov
Mon Sep 27 23:27:18 CEST 2010

This is a Linux box...  I know 350+ smtp transactions isn't that much traffic but, I'm polling for traffic and errors and I'm using the box for alerting circuits up/dn and plan on processing traps on it so, I wanted to be as efficient as possible to it.
That being said, it sounds like the headaches involved in running it in Daemon mode are greater than the performance gain.  Opinions?

>>> Steve Shipway <s.shipway at auckland.ac.nz> 9/27/2010 3:54 PM >>>

1.       Yes and no.  You need to use Include: to link them all into a master.cfg and then run MRTG with this, which means they must share all the same global declarations.  I’m working on a patch for MRTG to allow wildcards in the Include: directive but at the moment each file needs to be declared individually.  The recommended ‘best practice’ is to have one cfg file per device, then optionally link them all together with a ‘master.cfg’ file that uses Include: statements.  You can also have a
‘global.cfg’ file that is included by the various device cfg files, which can contain the various global declarations like LogFormat, Interval, WorkDir, and so on.  This forum post talks about it: http://www.steveshipway.org/forum/viewtopic.php?f=2&t=4093
2.       If you are running as a daemon, then you can use ‘Forks:’ (if you are running under linux/unix) to control the number of threads used, and tune this to make sure the checks are spread out over the 5min interval.  Here, we have home-grown code that makes certain of an even spread in scheduling.  The hit on the network is not really significant; it’s the hit on the MRTG system CPU and memory that is more a problem.  You can use RRDTool 1.4.x with rrdcached (in unix socket mode)  to
improve disk speed, but you need to use the development snapshot of MRTG for this to work.
3.       If you have ‘Logformat: rrdtool’ in the MRTG cfg file, then it will attempt to use RRDtool.  You may also need ‘Libadd:’ to specify the location of the RRDTool Perl libraries if you have not installed them into the site-perl path.  Note that, if in RRDTool mode, you will need to have a frontend installed (eg, routers2 or 14all) as MRTG will no longer generate the graph images every cycle.

Steve Shipway
ITS Unix Services Design Lead
University of Auckland, New Zealand
Floor 1, 58 Symonds Street, Auckland
Phone: +64 (0)9 3737599 ext 86487
DDI: +64 (0)9 924 6487
Mobile: +64 (0)21 753 189
Email: s.shipway at auckland.ac.nz
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From: Arvon Griffiths [mailto:Arvon.Griffiths at txdot.gov] 
Sent: Tuesday, 28 September 2010 8:07 a.m.
To: Steve Shipway; Denis Morin; mrtg at lists.oetiker.ch
Subject: New MRTG install... Run as Daemon and RRD setup?


I've got a test box up and I have installed the latest version of MRTG.  I have some questions-



Q1: If I use run as daemon, can I still have multiple CFG files (one for each router) or do I have to combine them all into one large (read: messy) CFG file?  If the answer is "you can have multiple CFG files", what is the big-picture as to how to set it up?


Q2: I have 350+ routers to check, if I run as daemon, how can I spread out the checks over a 5 minute period so the network isn't slammed at on minute 0,5,10,15, & etc.?




Q3: I'm either too dense to understand the instructions or they are not clear, how do you setup MRTG to use RRD tool?


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