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I modified 14all.cgi around line 67. Look for
<div> ### customize the html pages</div>
<div>and add the line</div>
<div> $ENV{'RRDCACHED_ADDRESS'} = 'unix:/var/tmp/rrdcached.sock';</div>
<div>just before it. Replace '/var/tmp/rrdchached.sock' with whatever path to the RRDcached socket you use.</div>
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</div>
<div>I run rrdcached with only</div>
<div> -w 5400 -f 21600 -m 666 -j path-to-journal -p path-to-pid -l unix:path-to-socket</div>
<div>and no other options.</div>
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</div>
<div>I keep my RRD files on a mirrored pair of solid-state drives. I have ~50,000 RRDs that are updated once an hour, and another ~5,000 that are updated every 5 minutes. The RRDs that are updated once an hour are very rarely looked at. RRDcached helps reduce
the write cycles on the SSD.</div>
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<div>Mike Mitchell<br>
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<div id="divRpF144188" style="direction: ltr; "><font face="Tahoma" size="2" color="#000000"><b>From:</b> mrtg-bounces+mike.mitchell=sas.com@lists.oetiker.ch [mrtg-bounces+mike.mitchell=sas.com@lists.oetiker.ch] on behalf of Pavel Ruzicka [pavouk@pavouk.org]<br>
<b>Sent:</b> Wednesday, August 01, 2012 5:18 AM<br>
<b>To:</b> Steve Shipway<br>
<b>Cc:</b> mrtg@lists.oetiker.ch<br>
<b>Subject:</b> Re: [mrtg] MRTG with RRDcached tuning<br>
</font><br>
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<div></div>
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Hello,</p>
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</p>
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> -s mrtg -m 0660 -l unix:/var/tmp/rrdcached.sock -l mrtg.auckland.ac.nz</p>
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> -l localhost -z 60</p>
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> </p>
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> -p /var/tmp/rrdcached.pid -t 4 -j /u01/rrdtool/journal -b /u01/rrdtool</p>
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> -w 1800 -O -a 6</p>
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</p>
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I tried -w 1800 and -z 60, but it still doesn't solve massive pdflush.</p>
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I don't understand exactly -z option. I understand from documentation</p>
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that when I set -z to 60 seconds, that it set random write delay between 0 and 60 seconds. When I have -w for 1800, that rrdcached writes files to disk in 60 seconds and -w option is not used. Is it true?</p>
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</p>
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> This has had a significant improvement on our previous IO problems.</p>
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> For the frontend, you could use Routers2 (which supports rrdcached directly</p>
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</p>
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I can't change easily frontend for historical reasons :-)</p>
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</p>
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> :). However, if you prefer to use 14all, then you can still do this via</p>
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> </p>
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> rrrdcached, at least if you are using Apache. Just set the</p>
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> RRDCACHED_ADDRESS environment variable appropriately in the web server so</p>
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> that it is set when the CGI is called, and this will make the 14all calls</p>
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> all use rrdcached, where possible.</p>
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> <Directory "/u01/www/cgi-bin"></p>
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> </p>
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> SetEnv RRDCACHED_ADDRESS unix:/var/tmp/rrdcached.sock</p>
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> </p>
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> </Directory></p>
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</p>
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I tried it, but it probably doesn't use rrdcached. How can I check it?</p>
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I have on graphs white space on the side. It looks like 14all.cgi use not updated rrd file.</p>
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</p>
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> You might want to consider using the trunk version of rrdtool, since this</p>
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> has more comprehensive rrdcached support for the various rrdtool functions.</p>
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</p>
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I prefer to use stable version, if it works.</p>
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Thank you very much for answers.</p>
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Best regards,</p>
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</p>
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Pavel</p>
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