Re: support for merged /usr in Debian

On Sun, 2016-01-03 at 23:04 +1300, Daniel Reurich wrote:
> On 03/01/16 22:33, Philip Hands wrote:
> > Daniel Reurich <daniel@centurion.net.nz> writes:
> > 
> > ...
> > > Because systemd doesn't work without /usr on the root partition isn't a
> > > good reason either.
> > 
> > You are right ... it is a poor reason, because it is pure fantasy.
> 
> Then why is it that since the introduction of systemd is having /usr on
> a separate partition suddenly considered evil and systemd complains
> loudly about it.  It always has worked and does work fine for me with
> sysvinit

systemd complains if it has to mount /usr itself.  This is because
mounting of local filesystems generally depends on various services and
udev hooks that may themselves depend on /usr.  This is also true when
using sysvinit.  Some services go through contortions to work before
/usr is mounted; others may behave subtly differently if it's a
separate filesystem.  We really need a simplified code path for
mounting /usr early on, and that is now provided by the initramfs.

> > > That just means systemd is broken by design and needs to be fixed.
> > 
> > If what you claimed were true, then I'd agree with you, but since all
> > the systems I've upgraded to systemd have a separate /usr, and are
> > working without any issue whatsoever, this drivel can be safely ignored.
> > 
> Then what's the problem and why are we even having this conversation
> about merged /usr???

As I understand it, merging /bin and /lib into /usr allows us to
support certain uses cases more easily - e.g. package installation in a
filesystem transaction, or sharing an NFS /usr filesystem.

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.