[mrtg] MRTG with RRDcached tuning

Steve Shipway s.shipway at auckland.ac.nz
Wed Aug 1 00:31:15 CEST 2012

As a comparison, we use the rrdcached options: 

    -s mrtg -m 0660 -l unix:/var/tmp/rrdcached.sock -l mrtg.auckland.ac.nz
-l localhost -z 60 

    -p /var/tmp/rrdcached.pid -t 4 -j /u01/rrdtool/journal -b /u01/rrdtool
-w 1800 -O -a 6


This has had a significant improvement on our previous IO problems.


For the frontend, you could use Routers2 (which supports rrdcached directly
:).  However, if you prefer to use 14all, then you can still do this via
rrrdcached, at least  if you are using Apache.  Just set the
RRDCACHED_ADDRESS environment variable appropriately in the web server so
that it is set when the CGI is called, and this will make the 14all calls
all use rrdcached, where possible.


<Directory "/u01/www/cgi-bin">

   SetEnv RRDCACHED_ADDRESS unix:/var/tmp/rrdcached.sock



You might want to consider using the trunk version of rrdtool, since this
has more comprehensive rrdcached support for the various rrdtool functions.


I still find rrdcached tuning a bit of a black art, and I've been
investigating it for some time.





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:  <mailto:s.shipway at auckland.ac.nz> s.shipway at auckland.ac.nz

P Please consider the environment before printing this e-mail 



From: mrtg-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch
[mailto:mrtg-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch] On Behalf Of
Pavel Ruzicka
Sent: Wednesday, 1 August 2012 1:14 a.m.
To: mrtg at lists.oetiker.ch
Subject: [mrtg] MRTG with RRDcached tuning




I succesfully enabled RRDCached for my MRTG setup.

I have mrtg-2.17.4 and rrdtool-1.4.7.

I am trying to spread kernel flushes in a time with enabling RRDCached.

Daemon runs with "-w 900 -z 900" parameters, but it looks like all kernel
flushes are still in a same time every 5 minutes.

Can somebody recommend me his parameters for rrdcached?


I want to try spread writes to one hour, but I want to graph actual data.

I use 14all.cgi and it doesn't support rrdcached. Have somebody 14all.cgi

patched for rrdcached support? I am not perl guru.

I know, that I must add something like this for RRD graph function

"--daemon unix:/var/run/rrdcached.sock" but I don't know how cleanly

to read path from mrtg config and add it to the code.

Mail of author bawidama at users.sourceforge.net doesn't work...


Best regards,


Pavel Ruzicka


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