computer:2:know

Linux (Rocky) journald log handling

 	useful journalctl commands:

		journalctl --no-pager

		journalctl --since "2025-01-01 00:00:00" --until "2025-01-15 23:59:59"

		journalctl --unit servicename.service

		journalctl --since 'today'

		journalctl -b			#boot session logs

		journalctl -b 0   # Shows logs from the current boot session

		journalctl -b -1  # Shows logs from the previous boot session

	

		check journal size:

		- journalctl --disk-usage

			Archived and active journals take up 130.5M in the file system.

			

		more detail information about journal:

		- journalctl  --header

			

		increase to 250M

		- backup config file: cp -p /etc/systemd/journald.conf /etc/systemd/journald.conf.save.2025-05-22

		- set Max Use to 250M: SystemMaxUse=250M

		- restart service: sudo systemctl restart systemd-journald

		

	see also:

		- https://linuxhandbook.com/clear-systemd-journal-logs/

		- https://betterstack.com/community/guides/logging/how-to-control-journald-with-journalctl/

		- https://community.hetzner.com/tutorials/optimize-journalctl-to-save-server-disk-space-in-linux





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if you see errors like that:

	errors:

		[Thu May 22 17:33:19 2025] systemd-journald[771]: Data hash table of /run/log/journal/sfasdf/system.journal has a fill level at 75.0 (26230 of 34972 items, 16777216 file size, 639 bytes per hash table item), suggesting rotation.

		[Thu May 22 17:33:19 2025] systemd-journald[771]: /run/log/journal/asfasdf/system.journal: Journal header limits reached or header out-of-date, rotating.



you can try to define SystemMaxUse  (don't forget to restart the service afterwards)
Computer and IT knowledge - things to know

Linux (Rocky) journald log handling
