Well, my battles with systemd continues... I had a box with limited disk space, and it was using over 4GB for just systemd journals. You can see the current journal usage with
$ sudo journalctl --disk-usage Journals take up 3.9G on disk.
I've tweaked this now, with a setting in /etc/systemd/journald.conf:
In addition, I ran a couple of commands from the command line:
$ sudo journalctl --verify $ sudo journalctl --vacuum-size=1G