Improving the reliability of file system monitoring tools (Collabora blog)

I actually had a server system (two, clustered with corosync/pacemaker) run with / fully ro. Only /home, subdirs (extra mountpoint) of /root and /var had been rw.
Login cluster for a server network. Back when even with grsecurity patches to lock down some more, including forbidden a remounting of things.

Worked pretty good, most of the time. Annoying to update (reboot into special rw-mode that didn't start services, update, reboot back to normal ro). Recently replaced with a new set of VMs and no more ro.

Sure nothing that one wants as standard, point is: It is actually *not* hard at all, to have it run so. And yes, it obviously depends on the exact usage of the system, as always.
(Server, not Desktop, that is).