[rrd-users] mrtg + rrdcached

Tobias Oetiker tobi at oetiker.ch
Tue Feb 2 08:00:10 CET 2010

Hi Steven,

Yesterday Steven Hartland wrote:

> I tried getting mrtg to work with rrdcached but it uses updatev
> in the rrdtool v1.2+ code path so it doesn't work. Looking through
> the code it seemed like there was no reason why if we forced the
> old 1.1 path it wouldn't work just fine.

except for the rrdtool fetch which is necessary to figure out of
alarms have to be raised which would force rrdcachd to flush the
cache on every round ... but if you do NOT use alarms, then things
should work fine.
> Thought it was worth a shot so tried it, and it works great!
> In fact it works better than great, it transformed out stats machine from a
> totally unusable box, due to excessive io, back
> to what it was before we started running mrtg on it :)
> Given this I thought I'd share this experience, so others can
> benefit.
> The patch attached is what we changed, its pretty rough with the
> cache server hard coded but it would be easy to fix that and works ;-)
> Hopefully future version of rrd will add updatev support to cached
> so this isn't needed but in the mean time we're just really happy
> to see the massive improvement that this new version brings, so
> thanks to everyone who worked on it!

there are ideas on how todo that ... but it is a bit tricky ...

>    Regards
>    Steve
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Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900

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