Performance analysis with iostat, sar, Ksar, collectd, and serverstats
Generating Graphs
Collectd is thus superior to serverstats when it comes to extensibility. However, anyone wanting to display basic data quickly in a web interface will be happy with serverstats. A functional configuration of Apache is already located in the doc
directory:
/usr/share/doc/serverstats# cp examples/apache.conf /etc/apache2/sites-available/serverstats.conf # a2ensite serverstats.conf # service apache2 reload
A cron job automatically creates the rrd
data in /var/lib/serverstats/rrd
every minute:
$ ls /var/lib/serverstats/rrd/ apache_localhost.rrd cpu.rrd disk_sda.rrd load.rrd memory.rrd traffic_proc_eth0.rrd users.rrd
After the Apache configuration is activated, the graphs are available immediately in the web interface, as shown in Figure 3.
Collectd does not provide its own interface for creating graphs. However, plenty of options are available for generating graphs from rrd
data. As a web interface, collectd-web
makes a solid impression (Figure 4). The best approach is to install it directly from the Git repository (Listing 8).
Listing 8
Apache Configuration
Collectd also stores its data in the /var directory
; /var/lib/collectd/rrd
has a subdirectory for each enabled plugin. Those not wanting to set up a web server for viewing graphs on their production system can either copy the data to another system or operate collectd as a client server. The network plugin allows data transfer to a central collectd server via UDP connections.
Conclusions
The tools described in this article will help you get better performance from your systems. Once you learn the basics, you'll find many ways to put these performance tools to work.
Infos
- Block layer statistics: https://www.kernel.org/doc/Documentation/block/stat.txt
- Monitoring IO Performance using iostat and pt-diskstats: http://www.percona.com/live/mysql-conference-2014/sites/default/files/slides/PLMCE_2014_MonitoringIO_2014-03-26_am_revised.pdf
- plotiostat logs: http://olausson.de/programs/plot-linux-system-stats
- Linux performance observability: http://www.brendangregg.com/Perf/linux_observability_sar.png
- Ksar: http://sourceforge.net/projects/ksar/
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