SysStat

Christian Külker

0.1.3

2024-03-21

Introduction

The SysStat package, authored by Sebastian Godard and licensed under GPLv2, is supported by 58 contributors on GitHub. This suite comprises several utilities aimed at monitoring system performance and usage:

  • iostat : Delivers CPU and input/output statistics for block devices and partitions.
  • mpstat : Provides statistics related to individual or multiple processors.
  • pidstat : Offers statistics for Linux tasks (processes), encompassing I/O, CPU, memory, and more.
  • tapestat : Supplies statistics for tape drives connected to the system.
  • cifsiostat: Generates CIFS statistics.

SysStat includes several tools intended for scheduling via cron or systemd to accumulate and record performance and activity data:

  • sar: “System Activity Reporter” gathers, reports, and stores system activity information
  • sadc: “System Activity Data Collector” acts as the system activity data collector, serving as a back-end for sar.
  • sa1: (shell procedure variant of sadc) Collects and stores binary data in the system activity daily data file, functioning as a front-end to sadc and is intended for execution via cron or systemd.
  • sa2: (shell procedure variant of sar) Creates a summarized daily activity report, operating as a front-end to sar and designed for cron or systemd execution.
  • sadf: “System Activity Data Formatter” presents data collected by sar in various formats (CSV, JSON, XML etc.), facilitating data exchange with other programs. This command also supports generating graphs for different activities recorded by sar in SVG format.

sa1 and sa2 are shell wrappers around sadc and sar. The difference is that the shell scripts handle corner cases and logging better and are therefore suggested to be used for crond.

System Statistics Collected by sar

  • Input/Output and Transfer Rate Statistics: Includes global, per device, per partition, and per network files-ystem data.
  • CPU Statistics: Covers global and per-CPU metrics, with support for virtualization architectures.
  • Memory Utilization: Encompasses statistics on memory, hugepages, and swap space.
  • Virtual Memory and Paging: Details virtual memory metrics, paging, and fault statistics.
  • Process Creation: Tracks process creation activity.
  • Interrupt Statistics: Includes global, per CPU, and per interrupt data, covering APIC interrupt sources, hardware, and software interrupts.
  • Network Statistics: Offers comprehensive data on network interface activity, failures from network devices, traffic statistics for IP, TCP, ICMP, UDP protocols (SNMPv2 standards), and IPv6-related protocols.
  • Specialized Statistics: Encompasses fibre channel traffic, softnet (software-based network processing), NFS server and client activity, socket statistics, run queue and system load, kernel internal tables utilization, swapping, TTY device activity, and power management (CPU clock frequency, fan speed, device temperature, voltage inputs).
  • Additional Metrics: Covers USB devices connected to the system, file-systems utilization (inodes and blocks), and Pressure-Stall Information statistics.

Debian

The Debian sysstat package integrates an entry within the system’s crontab. For comprehensive details, consult the file located at /usr/share/doc/sysstat/README.Debian.

For the display of all-day statistics with sar to work, data needs to be collected, but this is disabled per default under Debian. The Debian packages encompasses a system crontab file executing the sa1 script. However, it is initially in a disabled state, resulting in the non-collection of statistics. Consequently, executing sar without parameters typically results in an error, indicated as

Cannot open /var/log/sysstat/saXX: No such file or directory.

To rectify this issue and initiate data collection, activate the crontab function by executing:

        dpkg-reconfigure sysstat

and affirmatively responding to the inquiry regarding the activation of sysstat’s cron job.

If this option is enabled the sysstat package will monitor system activities
and store the data in log files within /var/log/sysstat/.

This data allows the sar(1) command to display system statistics for the whole
day.

If you don't enable this option, the sar(1) command will only show the current
statistics.

Activate sysstat's cron job?

            <Yes>                                            <No>

Furthermore, the package installs specific system crontab files, namely /etc/cron.d/sysstat and /etc/cron.daily/sysstat to collect data. Following the example section of the man pages to install cron jobs is not necessary. Undertaking such manual entries might result in concurrent executions of the sa2 script, potentially leading to operational errors.

Ansible and Command-line

To automate the installation and configuration of sysstat debconf can be used with Ansible to activate the cron job. However a non interactive configuration fails, because of the file /etc/default/sysstat. So the debconf configuration has to be done in one of the 3 ways:

  1. Before package installation non interactively
  2. After package installation interactively
  3. After package installation and removal of /etc/default/sysstat and non interactively

Before we write the Ansible debconf question, we would need to understand what question exactly is used in sysstat

debconf-show sysstat
* sysstat/enable: false
  sysstat/remove_files: true

On the command-line the following works after package installation.

debconf-show sysstat
* sysstat/enable: false
  sysstat/remove_files: true
# Edit /etc/default/sysstat and set ENABLED to "true"
echo sysstat sysstat/enable boolean true|debconf-set-selections
dpkg-reconfigure --frontend=noninteractive sysstat
debconf-show sysstat
* sysstat/enable: true
  sysstat/remove_files: true

With Ansible two more steps are needed.

  1. A value in /etc/default/sysstat need to be changed
  2. The sysstat server should be restarted.
# adm-nox.yaml
---
- hosts: role_client
  gather_facts: no
  become: yes
  vars:
      ns: adm_nox
      packages:
          # SysStat (iostat, ...) System performance tools for Linux
        - sysstat
  tasks:
    - name: "{{ ns }}: Install and update packages"
      apt:
        name: "{{ packages }}"
        state: latest
    - name: "{{ ns }}: Enable sysstat"
      lineinfile:
        path: /etc/default/sysstat
        regexp: '^ENABLED=".*"'
        line: 'ENABLED="true"'
        create: yes
    - name: "{{ ns }}: Pre-configure sysstat package"
      ansible.builtin.debconf:
        name: sysstat
        question: sysstat/enable
        vtype: "boolean"
        value: "true"
      become: yes
      register: dpkg_reconfigure
    - name: "{{ ns }}: Reconfigure sysstat package"
      ansible.builtin.shell:
        cmd: dpkg-reconfigure --frontend=noninteractive sysstat
      when: dpkg_reconfigure.changed
      become: yes
      notify: restart sysstat
  handlers:
    - name: restart sysstat
      service:
        name: sysstat
        state: restarted

Graphics

Projects related to sysstat that presents sar data in graphical format.

History

Version Date Notes
0.1.3 2024-03-21 Add graphics section
0.1.2 2024-03-08 Improve introduction, add Debian section, Ansible
0.1.1 2024-03-05 Add link to mpstat
0.1.0 2024-03-01 Initial release
  • SysStat