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