[hobbit] Devmon / MRTG

Buchan Milne bgmilne at staff.telkomsa.net
Mon Aug 17 16:49:18 CEST 2009

On Friday, 14 August 2009 15:08:33 mv652 at softhome.net wrote:
> Hi,
> Could I get a quick-and-dirty explanation regarding the Devmon
> implementation in Xymon 4.3.x?

Nothing has changed regarding Devmon in Xymon 4.3.x.

However, Xymon itself has some basic native SNMP support, which is new in 

> The way I understand it, Devmon provides SNMP capabilities to Xymon so the
> monitoring server can poll SNMP capable devices.
> How is this different to Integrating MRTF data into XYMON, for example?

Devmon only polls devices, does conversion and formatting of data, which it 
then sends to Xymon as a normal status message. A devmon RRD collector is now 
shipped with Xymon (as of 4.2.2), that allows RRD graphs to be created by 
Xymon for any test/template that includes data intended for this purpose 
(using the rrd option to the TABLE operator in the template file on the devmon 
side), if the test is mapped to use this collector (in the TEST2RRD variable 
in hobbitserver.cfg).

Besides the graphs, devmon will also change the "colour" of the tests based on 
thresholds, allowing you to alert on SNMP data (including non-graph data).

> If I am interesting in getting bandwidth for various device interfaces, I
> am assuming it is best to do via Devmon rather than integrate MRTG?

I think it is probably easier to get bandwidth graphs up with Devmon than with 
MRTG, and alerts based on link utilisation will be available out-the-box.

> Lastly, is there a readme / howto that explains devmon-xymon setup?

If you're on a distro that provides devmon, it is more or less a matter of:

# $install devmon

(where install=urpmi for Mandriva, or $install="yum install" on RHEL or CentOS 
if you have added the repo at e.g.  

# vi /etc/devmon.cfg

(set your SNMP community strings in the SNMPCIDS variable, the others should 
have adequate defaults)

# /etc/init.d/devmon readbbhosts

# /etc/init.d/devmon start

If you're adventurous, you could add the weathermap (see 

If you're not on a distro with packages available, please see the INSTALLATION 
and USING files shipped in the docs directory.


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