The case for the /usr merge

I am a strong proponent of this strategy. It makes logical sense that were / and /usr to be unified, we only need the root. We can just have a /usr → / symlink for backward compatibility.

The primary issue is one of upgrading; it's common to have a small / and large /usr, in which case users would run out of disc space on upgrade due to their / being filled up. However, migrating the smaller content of / to /usr is less likely to fail. This would not be an issue for clean installs. Given the appropriate documentation, and resizing of partitions prior to an upgrade, this is possible to work around.

The advantages are numerous, and it makes long-term sense to unify the two. On a modern package-managed system, the two are intimately tied, and the historical reasons for the split no longer apply. It's not just library dependencies that become simpler, we also have access to the glibc locale data from the moment init starts, meaning that it's possible to use UTF-8 locales in early boot, in addition to having no chance of NSS or PAM modules failing due to missing dependencies.

Regards,
Roger