[Bug 290885] Re: SRU: Backport of Boot Degraded RAID functionality from Intrepid to Hardy

[Steve Beattie]

On Thu, Dec 04, 2008 at 08:22:32PM -0000, Martin Pitt wrote:
> Dustin Kirkland [2008-12-04 12:51 -0000]:
> > Would would you think of adding a bit to the grub postinst that
> > detected if you were upgrading from a certain version, and if you have
> > root (or /boot) on a RAID device, and if so, run grub-install on that
> > device?
> 
> That doesn't seem to be a problem which got introduced with these
> patches? I. e. if you didn't have grub on the "other" device, it
> formerly would fail to boot, too?

No, it wasn't introduced in this fix, but it is getting fixed on new
(8.04.2) installations; it's just that existing installations will be
left with potentially unbootable systems in the event that the wrong
disk fails. It's just somewhat specious to claim that degraded raid boot
is fixed if it leaves users with a russian roulette situation of it not
working in 50% of the situations due to inadequacies in prior versions
of our installer.

> I am a bit nervous about automatically changing the boot sector of
> already installed systems, TBH. There might be cases where people
> explicitly configured it that way.  So adding a postinst snippet to
> detect this situation is fine, of course.

I too am leery of changing the boot sector of already installed systems as
well without admin intervention. This is why I was suggesting detecting if
/boot is on an md device and using the normal notification mechanisms at
our disposal. I'm afraid that if we don't do at least that, then admins
may not be aware of the potential situation.

While the issue is mentioned in the Software Raid FAQ at
https://help.ubuntu.com/community/Installation/SoftwareRAID, it's not
mentioned anywhere in the serverguide. I think relying on the help site
documentation is insufficient because you have to seek it out, and since
we don't issue update advisories for non-security updates, we're left
with either postinst notification methods or relying on the changelogs,
which are intended more for developer consumption than users.

Thanks.

-- 
Steve Beattie
<sbeattie at ubuntu.com>
http://NxNW.org/~steve/

-- 
SRU: Backport of Boot Degraded RAID functionality from Intrepid to Hardy
https://bugs.launchpad.net/bugs/290885
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