cislave3 ran out of diskspace again. I managed to to delete some stuff manually, but it's only a matter of time until it'll happen again. Some things that could be improved:
Limit the growth of /var/log/journal (see /etc/systemd/journald.conf)
Move more things to /mnt:
the JDK installs
MySQL (system) data (See http://serverfault.com/questions/487159/what-is-the-ibdata1-file-in-my-var-lib-mysql-directory)
There should also be a job which checks on the free diskspace regularly and fails if it is below a given threshold (unless we have something like this already; If not, I can help with setting it up). That way we'll know about the matter before actual jobs start to fail.