Ksar

Java applications may have gone somewhat out of fashion, but Ksar is still the easiest way to visualize sar data [5]. Ksar loads data records from a sar text file in the uncluttered interface; it does not accept binary files. Ksar will display the graph incorrectly if dates and numbers are not formatted as it expects. The environment variable LC_ALL guarantees the proper formats for the sar call:

LC_ALL=POSIX sar -A -f sa10 > ksar.out.txt

Ksar provides a selection of recorded data via the left sidebar. If you select a range, a graph displays the data (Figure 2).

Figure 2: Ksar graphically displays the statistics from a sar file.

Collectd and serverstats

Collectd and serverstats do not go into as much depth as iostat and sar. Instead, their strengths lie in data visualization. As is often the case, the round-robin database rrd is used as a data format. Serverstats and collectd are installed from the repositories in Ubuntu. For collectd, an installation without also installing recommended packages (--no-install-recommends) is sufficient and significantly minimizes the number of new packages.

Configuration

The main configuration file for collectd is /etc/collectd/collectd.conf. Plugins control the monitoring and logging of system resources in this file. Some plugins are already automatically enabled by default (e.g., load, memory, and disks). Numerous possibilities for expanding the default installation can be found on the collectd plugin page. A MySQL plugin is also available for database administrators. You can activate a new plugin by commenting out the associated LoadPlugin line. This can be configured in proprietary plugin sections – for example, for monitoring a specific device:

<Plugin disk>
              Disk "drbd1"
              IgnoreSelected false
</Plugin>

For serverstats, enable and configure the modules in /etc/serverstats/simple.php. However, the range of plugins here is not as comprehensive as with collectd.