How to configure SAR data collection on RHEL8
On RHEL8, it uses systemd instead of cron jobs to manage SAR data collection service.
Run the following command to check if the SAR data collection is started.
[root@h04-11 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux release 8.5 (Ootpa)
[root@h04-11 ~]# systemctl status sysstat-collect.timer
● sysstat-collect.timer - Run system activity accounting tool every 10 minutes
Loaded: loaded (/usr/lib/systemd/system/sysstat-collect.timer; enabled; vendor preset: disabled)
Active: inactive (dead)
Trigger: n/a
If it's not started, run the following command to start it.
[root@h04-11 ~]# systemctl start sysstat-collect.timer
[root@h04-11 ~]# systemctl status sysstat-collect.timer
● sysstat-collect.timer - Run system activity accounting tool every 10 minutes
Loaded: loaded (/usr/lib/systemd/system/sysstat-collect.timer; enabled; vendor preset: disabled)
Active: active (waiting) since Tue 2022-01-04 19:49:54 UTC; 1s ago
Trigger: Tue 2022-01-04 19:50:00 UTC; 4s left
Jan 04 19:49:54 h04-11 systemd[1]: Started Run system activity accounting tool every 10 minutes.
Check the sar file existence after a few minutes as below.
[root@h04-11 ~]# ls -ltr /var/log/sa
total 0
[root@h04-11 ~]# date
Tue Jan 4 19:50:25 UTC 2022
[root@h04-11 ~]# ls -ltr /var/log/sa
total 12
-rw-r--r--. 1 root root 11632 Jan 4 19:50 sa04
Check the default interval of SAR data collection as below.
[root@h04-11 ~]# systemctl cat sysstat-collect.timer
# /usr/lib/systemd/system/sysstat-collect.timer
# /usr/lib/systemd/system/sysstat-collect.timer
# (C) 2014 Tomasz Torcz <tomek@pipebreaker.pl>
#
# sysstat-11.7.3 systemd unit file:
# Activates activity collector every 10 minutes
[Unit]
Description=Run system activity accounting tool every 10 minutes
[Timer]
OnCalendar=*:00/10
[Install]
WantedBy=sysstat.service
To change the interval of SAR data collection, edit the systemd unit file as below.
[root@h04-11 ~]# export SYSTEMD_EDITOR=/usr/bin/vi
[root@h04-11 ~]# systemctl edit sysstat-collect.timer
Add the following to set the desired interval. In this example, we changed it from 10 minutes to 1 minute. The blank "OnCalendar=" directive is there to remove the original setting.
[Unit]
Description=Run system activity accounting tool every 1 minute
[Timer]
OnCalendar=
OnCalendar=*:00/1
Reload systemd service to apply the change.
[root@h04-11 ~]# systemctl daemon-reload
[root@h04-11 ~]# systemctl cat sysstat-collect.timer
# /usr/lib/systemd/system/sysstat-collect.timer
# /usr/lib/systemd/system/sysstat-collect.timer
# (C) 2014 Tomasz Torcz <tomek@pipebreaker.pl>
#
# sysstat-11.7.3 systemd unit file:
# Activates activity collector every 10 minutes
[Unit]
Description=Run system activity accounting tool every 10 minutes
[Timer]
OnCalendar=*:00/10
[Install]
WantedBy=sysstat.service
# /etc/systemd/system/sysstat-collect.timer.d/override.conf
[Unit]
Description=Run system activity accounting tool every 1 minute
[Timer]
OnCalendar=
OnCalendar=*:00/1
[root@h04-11 ~]# cat /etc/systemd/system/sysstat-collect.timer.d/override.conf
[Unit]
Description=Run system activity accounting tool every 1 minute
[Timer]
OnCalendar=
OnCalendar=*:00/1
[root@h04-11 ~]# systemctl status sysstat-collect.timer
● sysstat-collect.timer - Run system activity accounting tool every 1 minute
Loaded: loaded (/usr/lib/systemd/system/sysstat-collect.timer; enabled; vendor preset: disabled)
Drop-In: /etc/systemd/system/sysstat-collect.timer.d
└─override.conf
Active: active (running) since Tue 2022-01-04 19:49:54 UTC; 27min ago
Trigger: n/a
Jan 04 19:49:54 h04-11 systemd[1]: Started Run system activity accounting tool every 10 minutes.
To verify if the interval of SAR data collection is modified successfully, do the following.
[root@h04-11 ~]# sar -u -f /var/log/sa/sa04
Linux 4.18.0-348.2.1.el8_5.x86_64 (h04-11) 01/04/2022 _x86_64_ (32 CPU)
07:50:18 PM CPU %user %nice %system %iowait %steal %idle
08:00:18 PM all 0.11 0.00 0.13 0.00 0.00 99.76
08:10:08 PM all 0.11 0.00 0.13 0.00 0.00 99.75
08:14:08 PM all 0.12 0.00 0.13 0.00 0.00 99.74
08:15:35 PM all 0.12 0.00 0.13 0.01 0.00 99.73
08:16:18 PM all 0.12 0.00 0.14 0.02 0.00 99.72
08:17:07 PM all 0.10 0.00 0.13 0.00 0.00 99.77
08:18:18 PM all 0.12 0.00 0.13 0.00 0.00 99.75
Average: all 0.11 0.00 0.13 0.00 0.00 99.75
