Is it possible to reduce systemd-journald size stored format (and thus size)?

Question

I'm using systemd on raspberrypi machine with yocto based system. Recently I had some problems with redirecting messages to rsyslog.socket so I decided to get rid of rsyslog completely in favour of of journald.

After doing so I have noticed that size of journald files is much bigger than I previously thought it would be.

root@rpiDev: ~ $ journalctl -o cat > /tmp/journals-cat.txt
root@rpiDev: ~ $ journalctl -o export > /tmp/journals-exp.txt
root@rpiDev: ~ $ journalctl -o verbose > /tmp/journals-verb.txt
root@rpiDev: ~ $ journalctl -a -m > /tmp/journals.txt    ### This is what I need!
root@rpiDev: ~ $ journalctl -a -m -o verbose > /tmp/journals-everything.txt
root@rpiDev: ~ $ du -sh /tmp/journals* /var/log/journal/ ; journalctl --disk-usage
468.0K  /tmp/journals-cat.txt
15.7M   /tmp/journals-everything.txt
4.7M    /tmp/journals-exp.txt
4.9M    /tmp/journals-verb.txt
2.3M    /tmp/journals.txt
41.0M   /var/log/journal/
Archived and active journals take up 12.5M on disk.

Comparing the sizes it looks like binary files created by journald are much bigger than merged (-m) logs.

What I actually need is what is inside /tmp/journals.txt.

Question: Is it possible to reduce amount of stuff stored by journald in it's binary files to what I noticed when running journalctl -a -m?

In other words: can I disable storing all of the information that is not important to me and use journald just as I would syslog?

My problem can be solved by disabling permanent storing of journald logs and forwarding them to syslog, but maybe it is possible without bringing back rsyslog?

EDIT:

Parameters mentioned by some users do not help me here.

• Using SystemMaxUse= and RuntimeMaxUse= only sets the maximum size of the files stored- I can have smaller files with the same amount of not needed info and therefore even less actual logs.
• Using MaxLevel...= sets the maximum log level stored in the journal. That is also not what I need here.

EDIT2:

My solution:

I have decided to store logs in syslog (I use rsyslog).
In my journald.conf I have set Storage=volatile and used SystemMaxUse=64M and RuntimeMaxUse=64M to limit disk usage by journald.
I also enabled ForwardToSyslog=yes so now I have my old syslog solution working and I'm also able to view runtime journald logs.

Answer 1

Edit /etc/systemd/journald.conf to specify how much space the journal can use, both in memory and on disk.

See man journald.conf for an in-depth explanation of the settings it contains.