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sysstat

The sysstat package is a collection of performance monitoring tools for Linux. It provides comprehensive statistics about system usage, including CPU, memory, disk I/O, network, and more.

Core Tools in sysstat​

The sysstat package includes several important utilities:

  • sar (System Activity Reporter): Collects, reports, and saves system activity information. It is arguably the most powerful tool in the suite.
  • iostat: Reports Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.
  • mpstat: Reports individual or combined processor related statistics.
  • pidstat: Reports statistics for Linux tasks (processes) : I/O, CPU, memory, etc.
  • nfsiostat: Reports input/output statistics for network file systems (NFS).
  • cifsiostat: Reports statistics for CIFS filesystems.

Installation and Configuration​

The sysstat package is available in most Linux distributions' standard repositories.

Installation​

  • Debian/Ubuntu: apt-get install sysstat
  • RHEL/CentOS: yum install sysstat

Configuration​

To enable data collection for historical reporting (used by sar), you must configure and start the sysstat service.

  1. Edit /etc/default/sysstat (on Debian/Ubuntu) and set ENABLED="true".
  2. Start the service: systemctl start sysstat
  3. Enable it on boot: systemctl enable sysstat

Data collection is managed by cron jobs or systemd timers, typically gathering data every 10 minutes and storing it in /var/log/sysstat/.

Using iostat​

iostat is primarily used for monitoring system input/output device loading.

  • iostat: Shows a brief overview of CPU and disk I/O.
  • iostat -x 2 5: Displays extended statistics (-x), every 2 seconds, 5 times.
  • iostat -p sda: Displays statistics for block device sda and all its partitions.

Using mpstat​

mpstat is used to monitor CPU utilization on multiprocessor systems.

  • mpstat: Shows overall CPU statistics.
  • mpstat -P ALL: Shows statistics for all individual processors.
  • mpstat 1 3: Shows overall CPU statistics every 1 second, 3 times.

Using pidstat​

pidstat is useful for monitoring specific processes.

  • pidstat -u: CPU statistics for active processes.
  • pidstat -r: Memory statistics for active processes.
  • pidstat -d: I/O statistics for active processes.
  • pidstat -p 1234 1 5: Shows statistics for process ID 1234 every 1 second, 5 times.