Bug#914897: debootstrap, buster: Please disabled merged /usr by default
On Mon, 03 Dec 2018 at 17:45:11 +0100, Svante Signell wrote:
> On Sun, 2018-12-02 at 21:04 +0100, Marc Haber wrote:
> > moving hundreds of megabytes from /usr to / over time.
>
> This solution was proposed by GNU/Hurd several years ago, and was scrapped due
> to not being big enough player in the *NIX world:
> https://www.gnu.org/software/hurd/faq/slash_usr_symlink.html
This did make more sense than the arbitrary split, but with hindsight I'm
glad it did't take off, because the /usr merge does have an important
advantage over the old Hurd proposal: it takes all the static OS files
(which are more similar than they are different) and groups them
together. Unifying those files into / as Hurd used to do would have
made it harder to disentangle them from the sysadmin-modifiable /etc
directory, which needs to be on the root filesystem anyway because it's
where we find /etc/fstab.
If I remember correctly, the people who implemented the /usr merge in
Fedora actually started by proposing that the static files were unified
into / (as in older Hurd versions), and later switched their design
around when they realised that grouping those directories together would
be better.
The name /usr is indeed an unfortunate historical accident.
> We think that we have found a more
> flexible solution called union filesystems, which allow to create virtual
> filesystems which are the union of several other filesystems. However, support
> for union filesystems is still in early development.
I get the impression that union mounts in Linux aren't completely reliable
either (and have some awkward corner-cases), so solutions that don't
require them seem likely to be more robust.
smcv
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