Re: [[Patch mdadm] 2/5] Move the files mdmon opens into /dev/ to support handoff after pivotroot

[Michael Evans <mjevans1983@gmail.com>]

On Sat, Feb 6, 2010 at 1:46 PM, martin f krafft <madduck@debian.org> wrote:
> also sprach Dan Williams <dan.j.williams@intel.com> [2010.02.07.1007 +1300]:
>> This comment makes me see Neil's argument in a different light,
>> (hopefully I am not mischaracterizing it), but essentially we are
>> waiting for the standards to catch up with this new class of
>> program. FUSE, CUSE, and mdmon belong to a class of programs that
>> move traditionally exclusive kernel space functionality to
>> userspace. Debian's /lib/init/rw looks to be a response to this
>> grey area of the standards (not that I have any familiarity with
>> the LSB).
>
> I have not read the full thread for lack of time, but I would like
> to chime in that I favour user-space over kernel-space any day: it
> makes for stabler systems, better interfaces, and easier upgrades
> — even though it's definitely more work for the distro maintainers.
>
> So mdmon seems like a good idea, even though some details might need
> to be worked out to everyone's satisfaction yet.
>
> I agree with Dan that this trend is new and that slow-moving
> standards like the FHS have yet to catch up. But they cannot catch
> up if distros don't explore the field. Debian's latest move in this
> exploration was indeed /lib/init/rw, but it's questionable, not only
> because it's a tmpfs, which makes it unusable for e.g. md bitmaps
> — unless we invented a place that moved to persistent storage as
> early as possible, in a way that would make it accessible early
> during the next boot. But now I am diverting the topic…
>
> --
>  .''`.   martin f. krafft <madduck@d.o>      Related projects:
> : :'  :  proud Debian developer               http://debiansystem.info
> `. `'`   http://people.debian.org/~madduck    http://vcs-pkg.org
>  `-  Debian - when you have better things to do than fixing systems
>
> "there are two major products that come out of berkeley: lsd and unix.
>  we don't believe this to be a coincidence."
>                                                 -- jeremy s. anderson
>
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Shouldn't all /state/ information be held in the kernel in some form
and exported via one of the virtual filesystems? (dev, proc, sysfs)

This way if some userspace need exists the file can be read.  If some
kernel access is required it's already within known structures.
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