UsrMove feature breaking "yum upgrade" upgrades from older releases to F17?

Miloslav Trma─Ź mitr at volny.cz
Sat Jan 28 09:47:35 UTC 2012


On Fri, Jan 27, 2012 at 7:43 PM, Jef Spaleta <jspaleta at gmail.com> wrote:
> If you haven't read the new summary write-up on the benefits of the
> /user feature that I think you would benefit from reading it.
> http://www.freedesktop.org/wiki/Software/systemd/TheCaseForTheUsrMerge
>
> If you have read it, then I fear you either don't fully understand or
> do not value the long term benefits associated with the filesystem
> snapshotting nor the utility of having read-only shared vendor
> supplied /usr across many guest instances.

Apart from fixing things that are not a problem[1], the
stateless/snapshotting benefits are, AFAIK, just vaporware promises.
I can't see they can work as stated because /etc and /var are quite
strongly bound to the details of contents of the newly proposed /usr -
and these objections were raised back when FESCo first discussed this
feature.

Actually getting a stateless system would require first defining what
is "state" and what is "OS" (and that question will have several
different answers, for good reasons!), and then doing the actual work
of separating the two.  We already have a readonly-root facility in
initscripts, and I think that one is doing it right - giving the
people that want to use these (non-default, comparatively rarely-used
and site-specific) features the power to create a stateless system
without burdening the most common users with it.
    Mirek

[1] Improved compatibility with Solaris - Seriously? We didn't need
that level of compatibility back when Linux was a small niche, why
would we care now? I feel mildly insulted by that argument.


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