As this answer suggests, the way to enable storing logs across boots is:
# mkdir /var/log/journal # systemd-tmpfiles --create --prefix /var/log/journal # systemctl restart systemd-journald
But when I do it, it breaks the output of the
sudo journalctl -fu myservice commands, because the messages aren't coming out immediately any more.
journalctl just doesn't follow the log, and you have to restart journalctl.
Ubuntu 15.04, systemd 219-7ubuntu6. I saw a similar bug report https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=755062
Is that journalctl thing reliable?