[mrtg] Configuring MRTG/rrdtool with <1 minute intervals

Daniel J McDonald dan.mcdonald at austinenergy.com
Wed May 28 13:25:45 CEST 2008

On Wed, 2008-05-28 at 11:53 +1200, Steve Shipway wrote:
> > > I am currently attempting to configure MRTG/rrdtool to poll some SNMP
> > > statistics at a rate under 1 minute.
> >
> > This is not possible using MRTG.  Check the MRTG documentation.  Although
> > RRDTool can support intervals as low as 1 second, MRTG cannot.
> >From Tobi's email, it seems that MRTG can now accept decimal
> intervals (I wonder when this was added? I'm behind the times). 

2.15.0.  From the changelog:
      * mrtg running with rrdtool can now do sub-minute resolution if
        the interval is specified like that: 0:30 ... note that you can
        not change the resolution of an existing rrd file. So this will
        only have the desired effect on new rrds. Also note that the
        graphing frontend may need changes too to be able to deal with
        the new interval type. Internally interval is now a float!

>  However it still holds that the routers2 frontend will not show
> graphs for smaller periods than 6 hours, IE, 1min-per-pixel, so you'll
> need to have some other way of displaying them.  I think 14all and
> default mrtg-rrd will also only show Daily graphs (IE, 5min interval)
> and not smaller (but I may be behind the times on these, too?)

No, you're not behind the times on them.  Neither of those projects has
seen an update since 2003.  mrtg-rrd is particularly broken - it uses
its own parser rather than relying on the one in MRTG_lib.pm, so it
can't keep up with new features in later versions of mrtg without
serious hacking.

We're all counting on you, Steve!  Thanks for being an active

Daniel J McDonald, CCIE #2495, CISSP #78281, CNX
Austin Energy

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