mrt 032016

When you use rrdtool, it can happen that you first create your databases, then collect a whole bunch of data and decide later you want more accuracy/longer periods.
Especially when using zenoss (the monitoring solution I mostly work with at Kangaroot), which uses very conservative RRD settings by default (i.e. 5-minute intervals for only the first 50 hours). Zenoss provides a way for you to change the way RRD’s are created, but not to apply those settings to already existing RRD files, which I found out *after* I started monitoring everything ūüėČ

rrdresize can help: it (just) adds or removes locations for rows.
In my case it was not good enough because zenoss uses a variety of resolutions (step sizes), and so if you add rows to all of them rrdtool – when graphing – will often pick a higher resolution RRA that just had rows added (and hence contain unknown values), even though you have the values, albeit at a lower resolution.

So you need a way to update all rows in the RRA’s.
I found a perl tool that does just that. (I think, I didn’t study all details). So, you install that in your /home/zenoss for instance and then you run the following script, which creates new rrd files with the new settings and uses the perl script to copy all data into it.

# invoke me like this:
# find /usr/local/zenoss/zenoss/perf/ -name '*.rrd' -exec ./ {} \; >> newrrd-logfile

[ -d "$backupdir" ] || mkdir -p "$backupdir" || exit 2
[ -d "$newdir"    ] || mkdir -p "$newdir" || exit 2
[ -f "$file"      ] || exit 3

echo "Processing $file .."
base="`basename "$file"`"
[ ! -f "$backupdir/$base" ] || mv "$backupdir/$base" "$backupdir/$base".old || exit 4
cp "$file" "$backupdir/$base"
cd "$newdir" && rrdtool create "$base" \
--step '300' \
--start '1230768000' \
'DS:ds0:GAUGE:900:U:U' \
'RRA:AVERAGE:0.5:1:122640' \
'RRA:AVERAGE:0.5:6:55536' \
/home/zenoss/ "$backupdir/$base" "$base" | grep -v 2009 # hide some output
cp "$base" "$file" || exit 5
echo "Done"

Oh and btw, rrdwizard is a cool webapp when you’re feeling too lazy/have forgotten how to write rrdtool commands

okt 102014

This HowTo describes how to install the transcoding tools under Ubuntu 14.04
For Open Source Transcoding  you have to install the transcoding tools (MPlayer, mencoder, ffmpeg, flvtool2, faststart). As the Ubuntu packages do not support all required formats, we have to compile the required tools.

In most cases please just copy & paste the code into your shell and execute the commands as root.
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mrt 312014

Bij het herstarten van Apache verschijnt de error: NameVirtualHost *:80 has no VirtualHosts

Dit probleem ontstaat als meerdere keren NameVirtualHost is gedefinieerd;

Somewhere in your configuration, probably in the Apache default configuration file (I think /etc/apache2/httpd.conf in Ubuntu? someone can correct me in the comments), is a line that looks like:

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nov 052013

Munin is een applicatie dat wordt gebruikt om te monitoren. Het genereerd statistieken en zet het om in overzichtelijke afbeeldingen.

In  deze post beschrijf ik hoe met Munin MySQL databases kan worden gemonitord.
Echter komt er een foutmelding als een InnoDB database wordt gemonitord.

InnoDB is is een snelle MySQL engine. Echter is deze deprecated.
Als InnoDB uit staat MySQL zal Munins plugin mysql_connections een foutmelding geven:

# munin-run mysql_connections
DBD::mysql::st execute failed: Unknown table engine 'INNODB' at /etc/munin/plugins/mysql_connections line 958.
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