2011/10/25 Harald Hoyer <harald.hoyer(a)gmail.com>:
> If anything, wouldn't it make more sense to move stuff in the
opposite
> direction, from /usr/bin to /bin ? "usr" doesn't really mean anything
> - originally it was used because the filesystem format couldn't
> support more than 64MB(?) in a single volume, so the system had to be
> split to / and /usr.
You want your OS in one directory and not split in 4 toplevel directories.
I'd actually find it more natural to have _my data_ (whatever "data"
means here, probably including httpd configuration and ssh keys - and
defining this well is probably a difficult problem) in one directory
and not all over / . I can rebuild "the system" anytime, and in a
sense I don't really care about "the system", but I need to backup "my
data".
> Also, Fedora already sort-of has a system for stateless OS images
-
> see /etc/sysconfig/readonly-root. What will happen to it?
It does not go away with this feature.
Does it make sense to have two separate facilities for stateless OS
images? How do they interact? When do I use one instead of the
other?
> And more importantly, what is the overall benefit to our users?
I
> can't find anything compelling in the "Benefit to Fedora" section (if
> /usr/ can be snapshotted, why not / ?); AFAICT this requires changing
> 257 packages for mostly aesthetic reasons.
It's not only an aesthetic issue. This enables possibilities, which were
not doable before.
- snapshot /usr (with btrfs)
If my stateful data were mounted to /var/lib/*, why
couldn't I
snapshot the read-only / volume just as easily?
- hot swap the OS (/usr) with another version
Can I really do
that when various processes will be running and have
/usr/lib*/libc.so.* mapped?
- mount /usr ro and keep the rootfs writeable
OK... but again,
we supposedly have that functionality with
/etc/sysconfig/readonly-root.
- share the _whole_ OS with other machines
... as long as I
manage to update the configuration in /etc at the
same time I update the OS image. Perhaps possible, but non-trivial.
Mirek