On 02.05.2015 15:40, Hendrik Boom wrote:

> On Thu, Apr 30, 2015 at 11:42:24PM +0200, Didier Kryn wrote:
>> Le 30/04/2015 20:16, John Morris a écrit :
>>> The FHS was carefully designed to accomodate things like NFS root,
>
> Years ago I heard that /usr could be mounted read-only, and even shared
> between different running copies of Linux by an NFS mount.
>
> But I've never seen a distro that took this seriously enough that a
> routine upgrade (with something like aptitude upgrade) would work.

I broadly use a simple configuration: readonly root over NFS and rw /var.
In this manner I've setup clusters for computational chemistry, student
computer classes, nowadays thin clients and my own "desktops".

Back to the times of RedHat 5 it was not so simple: custom /dev stuff,
generally needed some local storage for /var because of RAM shortage and
so on. Since then, we have automagic /dev, aufs to forget completely
about local hdd, less packages ignore fs layout in non-compatible manner.

Modern Debian works in readonly root like a charm. I update it within
chroot on NFS server without any error. Changes over standard
distribution are minor:
/var over aufs tmpfs(rw)+nfs(ro),
some symlinks (perhaps not at all today),
postinst script to update tftp storage after updating kernel/initrd stuff.

My friend used readonly /usr over NFS for years, which is more
conventional setup than mine.

I kindly ask all developers, including of Devuan, who plan to change FS
layout significantly, to think twice and not break things by assuming
"typical usage".

--
sa