Bug#914897: debootstrap, buster: Please disabled merged /usr by default
On Sun, Dec 02, 2018 at 11:31:13PM +0100, Marco d'Itri wrote:
> On Dec 02, Wouter Verhelst <wouter@debian.org> wrote:>
> > One thing that has not been answered yet in this discussion (and if the
> > TC is to make a decision about it, I think it should be) is "why are we
> > doing this". That is, what is the problem that usrmerge is meant to
> > solve, and how does it attempt to solve it? As far as I know, the reason
> > usrmerge exists is so that no files will be installed in /bin anymore;
> > but that seems like an XY problem.
> https://lists.debian.org/20181121140542.GA31273@espresso.pseudorandom.co.uk
That post is too long-winded and touches so many unrelated issues that it's
difficult to respond to it. Could you please give us a terse list of
claimed benefits? Without a clear claim, it's too easy to both do or be
accused of doing a straw-man.
By my reading, most of that post either falls into the XY problem or
explains how merged-usr fixes problems caused by merged-usr itself.
That leaves only one concrete claim:
* that merged-usr makes it easier to have a part of the system immutable
(be it for recovery purposes or for sharing)
My response to that claim is: there's a long list of techniques that can be
used for such an effect without sweeping distribution-wide changes. Heck,
not even a couple of hours ago I restored from a snapshot multiple times in
order to troubleshoot a broken udev problem. Here's your "This means you
always have a known-working filesystem to fall back on (if the most recently
updated filesystem doesn't boot, use the other one)". Or, container
sharing: works fine for me without merged-usr either. Thus, in order to
make this claim stick, you need to not only list its benefits but also
explain how it's better than other approaches: filesystem-based (btrfs, ZFS,
XFS), vfs-based (various overlays), lvm-based/-like, block-device based,
multiple mounts, etc. And, many of those can do CoW which is so much better
than immutability.
(Please explain if I understood you wrong.)
Meow!
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