On one server running openSUSE 12.1 (upgraded from 11.x) time to time OpenLDAP service stops. According to logs something/someone stops it using systemd API (the API that systemctl command uses), but probably without calling any command line (for OpenLDAP systemd calls /etc/init.d/ldap, we have added ps fax >> /var/log/stopped_ldap to it, we see that the script gets called, but don't see it's caller nor anything calling systemctl). How to enable logging of systemd calls and callers to pinpoint what exactly is stopping OpenLDAP.