Collectd

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Collectd is a daemon for collecting, storing and exporting system and application performance metrics periodically. It has many built-in plugins from which it can gather metrics.

It can export to various formats and can send notifications/emails at certain thresholds.

Installation

A collectdAUR package can be installed from the AUR. This package is configured to build with many common plugins.

Configuration

The default configuration can be found at /etc/collectd.conf.

A plugin can be enabled with LoadPlugin.

For instance to enable the mysql plugin just uncomment: 

#LoadPlugin mysql

For more info see collect.conf(5).

Warning: LoadPlugin lines in the default config starting with ## are for plugins which are not built. They can not be enabled.

Creating Graphs

Collectd has no built-in frontend. It does support many output formats and many front-ends are built specifically with collectd in mind.

See this list of front-ends.

Collectd's collected data can be found in /var/lib/collectd/<hostname>.

Contrib scripts

Collectd also has a contrib folder in its repository. This contains various contributed scripts. Many of these are meant for use with cgi.

For instance install and run collect2html.pl to generate an html webpage with a graph for each collected metric.

Rrdtool

The default output format of collectd is rrd. This data can be graphed using rrdtool.

To graph the last hour of memory usage: 

rrdtool graph output.png \
                --start end-1h \
                --end now \
                --title "Memory Usage - Last Hour" \
                --width 600 \
                --height 200 \
                DEF:avg=/var/lib/collectd/localhost/memory/memory-used.rrd:value:AVERAGE \
                LINE1:avg#FF0000:"Memory Used"

See also