[mrtg] integrate rrdcached with mrtg
s.shipway at auckland.ac.nz
Wed Nov 3 22:02:32 CET 2010
> I use RRDCACHED_ADDRESS environment variable:
> export RRDCACHED_ADDRESS=127.0.0.1
> I run rrdcached as:
> rrdcached -l 127.0.0.1 <more params>
> but when I run mrtg I get:
> ERROR: Cannot update file.rrd with
> The "RRDCACHED_ADDRESS" environment variable is defined, but "dummy"
> work with rrdcached. Either unset the environment variable or use
> "update" instead
For MRTG to work with rrdcached, you need to have a patched MRTG (2.16.4) (grab the latest dev snapshot) as it will try to use updatev by default which is not supported by rrdcached. Also, you have to use UNIX sockets (not TCP) unless you have the latest development version of RRDTool (1.4.999+) as earlier versions of rrdcached do not support create/last/info. You can pick these up from Tobi's website. With the patched MRTG, you can use 'RRDCached: unix:/var/tmp/rrdcached.sock' (or similar) in your MRTG cfg file instead of setting RRDCACHED_ADDRESS if you want to. Finally, if using rrdcached, MRTG Thresholds will no longer work, and you will probably need to make sure your frontend properly supports rrdcached else you may end up with the graphs updating late (the latest routers2 beta has built-in rrdcached support).
I have it working here successfully; I'll be giving a presentation on it at LISA10 in San Jose next week -- email me if you'd like a copy of the powerpoint.
ITS Unix Services Design Lead
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