System Activity Reporter or SAR is a program utility for analyzing Linux system performances. SAR measures CPU activity, memory paging, network issues, process and thread allocation, etc.
It collects data every 10 minutes and it gathers in the /proc filesystem. In this blog post, we will use the Ubuntu 22.04 as OS. You can choose any Linux distro you want.
Installing SAR on Ubuntu 22.04 is a straightforward process; installation and configuration may take up to 10 minutes. Let’s get started!
Prerequisites
- A server with Ubuntu 22.04 as OS
- User privileges: root or non-root user with sudo privileges
Step 1. Update the System
We assume that you have a fresh installation of Ubuntu 22.04. That’s why we need to update the package to the latest versions available.
sudo apt-get update -y && sudo apt-get upgrade -y
Step 2. Install SAR
The SAR package is, by default, included in the sysstat package. To install SAR execute the following command:
sudo apt-get install sysstat
Once installed, start and enable the service:
sudo systemctl enable sysstat && sudo systemctl start sysstat
Check if the service is up and running:
sudo systemctl status sysstat
You should receive the following output:
root@host:~# sudo systemctl status sysstat
● sysstat.service - Resets System Activity Logs
Loaded: loaded (/lib/systemd/system/sysstat.service; enabled; vendor preset: enabled)
Active: active (exited) since Fri 2023-09-08 09:37:51 CDT; 1min 20s ago
Docs: man:sa1(8)
man:sadc(8)
man:sar(1)
Main PID: 8753 (code=exited, status=0/SUCCESS)
CPU: 18ms
Sep 08 09:37:51 host.test.vps systemd[1]: Starting Resets System Activity Logs...
Sep 08 09:37:51 host.test.vps systemd[1]: Finished Resets System Activity Logs.
Step 3. Enabling SAR
After installation, SAR is not enabled by default. To enable it open the /etc/default/sysstat file with your favorite editor and modify it to look like this:
# # Default settings for /etc/init.d/sysstat, /etc/cron.d/sysstat # and /etc/cron.daily/sysstat files # # Should sadc collect system activity informations? Valid values # are "true" and "false". Please do not put other values, they # will be overwritten by debconf! ENABLED="true"
Save the file, close it, and restart the service.
sudo systemctl restart sysstat
As we mentioned in the lead, the SAR collects data every 10 minutes. This can be checked and confirmed in the /etc/cron.d/sysstat file.
root@host:~# cat /etc/cron.d/sysstat # The first element of the path is a directory where the debian-sa1 # script is located PATH=/usr/lib/sysstat:/usr/sbin:/usr/sbin:/usr/bin:/sbin:/bin # Activity reports every 10 minutes everyday 5-55/10 * * * * root command -v debian-sa1 > /dev/null && debian-sa1 1 1 # Additional run at 23:59 to rotate the statistics file 59 23 * * * root command -v debian-sa1 > /dev/null && debian-sa1 60 2
Step 4. How to use SAR
In this final step, we will provide you with some commands about SAR usage.
For example, to check the CPU usage execute the following command:
sar -u
You should get output similar to this:
root@host:~# sar -u Linux 5.15.0-83-generic (host.test.vps) 09/08/2023 _x86_64_ (3 CPU) 06:37:51 AM LINUX RESTART (3 CPU) 06:40:16 AM CPU %user %nice %system %iowait %steal %idle 06:50:16 AM all 0.01 0.00 0.15 0.00 0.05 99.79 Average: all 0.01 0.00 0.15 0.00 0.05 99.79 06:50:40 AM LINUX RESTART (3 CPU) 07:00:11 AM CPU %user %nice %system %iowait %steal %idle 07:10:16 AM all 0.01 0.00 0.28 0.00 0.12 99.59 07:20:16 AM all 0.01 0.00 0.19 0.00 0.03 99.77 Average: all 0.01 0.00 0.23 0.00 0.08 99.68
To display free and available memory, execute the following command:
sar -r
You should get output similar to this:
root@host:~# sar -r Linux 5.15.0-83-generic (host.test.vps) 09/08/2023 _x86_64_ (3 CPU) 06:37:51 AM LINUX RESTART (3 CPU) 06:40:16 AM kbmemfree kbavail kbmemused %memused kbbuffers kbcached kbcommit %commit kbactive kbinact kbdirty 06:50:16 AM 2933644 3495596 220264 5.50 46204 716808 1051440 20.80 494836 373528 0 Average: 2933644 3495596 220264 5.50 462
To check the used Swap space, execute the following command:
sar -S
You should get output similar to this:
root@host:~# sar -S Linux 5.15.0-83-generic (host.test.vps) 09/08/2023 _x86_64_ (3 CPU) 06:37:51 AM LINUX RESTART (3 CPU) 06:40:16 AM kbswpfree kbswpused %swpused kbswpcad %swpcad 06:50:16 AM 1048568 0 0.00 0 0.00 Average: 1048568 0 0.00 0 0.00 06:50:40 AM LINUX RESTART (3 CPU) 07:00:11 AM kbswpfree kbswpused %swpused kbswpcad %swpcad 07:10:16 AM 1048568 0 0.00 0 0.00 07:20:16 AM 1048568 0 0.00 0 0.00 07:30:16 AM 1048568 0 0.00 0 0.00 07:40:16 AM 1048568 0 0.00 0 0.00 Average: 1048568 0 0.00 0 0.00
Step 5. SAR command in more detail
If you want to know more about the sar command, just execute the following line of code:
man sar
You will get an output with a full description of every option for the sar command.
Hopefully, our guide on how to install and use SAR on Linux was of help to you. We would love to hear from you now:
Did we skip something essential, or do you need a more detailed explanation about any of the steps? What are some other topics or tutorials you would want us to delve into?
Please feel free to share your thoughts in the comment section.