Comment # 2 on bug 1113256 from Stefan Hundhammer

Please remember that the reason for that minimum size is not /tmp and /var, but
the disk space needed for snapshots and CoW in general.

Whenever you receive package updates, that consumes more disk space; it's more
for a rolling release like Tumbleweed, but even Leap gets regular updates. It
is very advisable to have reserve disk space for those updates themselves
(because packages tend to grow over time), and for Btrfs users, as well for
snapshots.

My moderately-sized Leap 15.4 that I use for development has a 30 GiB ext4 root
filesystem of which 13 GiB are used, 9.7 GiB for the ~2900 packages that I have
installed (and the home directory is on a separate filesystem).

My experience with a Btrfs root filesystem (with TW) of the same size was that
it was constantly running full. Reserves are strongly advised, in particular
for Btrfs.

We live in the age of Terabyte disks; even SSDs tend to have 256 GiB these
days. A user being confronted with the dreaded "disk full" error has a real
problem to fix that (unless using LVM, but not all do); for most users,
reinstalling is the only viable option, and that is painful.


Also, the days of a separat /usr are gone after the decision to merge /usr and
the root filesystem, so pretty much every part of the system that consumes disk
space is now on the root filesystem, so the distinction between / and /usr has
become moot.


So all in all, this would be micro-optimization in an area where we would
probably do more harm than good. We should probably be more generous with
reserving disk space, not more parsimonious.