grub legacy to grub2 upgrade path

grub legacy to grub2 upgrade path

[ryuo]

I am a senior developer for the Frugalware Linux distribution, and I am
trying to find an upgrade path so we can leave grub legacy behind. Normal
disk installations work perfectly under testing, however I have found a
snag with RAID installations we have to support that were setup under grub
legacy, which we installed under metadata 0.90 because of the limitations
of grub legacy.

The problem appears to be this bug: http://savannah.gnu.org/bugs/?34250

It effects RAID setups that only use a single partition per disk, and in
my tests I got errors from grub-install of this kind:
http://frugalware.org/paste/13418

The problem seems to be that grub2 is unable to deduce *where* the RAID
really is.

I tried installing to the MBR of both disks and RAID device, using a
simple grub-install command. (grub-install /dev/md0, etc.) I did my
testing with a mostly vanilla 1.99 grub2.

If any of our users happen to run into this issue, what are we to tell
them to do? I'd like another option than forcing them to have to redo
their RAID setup.

Any insights would be appreciated.

Re: grub legacy to grub2 upgrade path

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 23.02.2012 05:14, ryuo@frugalware.org wrote:
> I am a senior developer for the Frugalware Linux distribution, and I am
> trying to find an upgrade path so we can leave grub legacy behind. Normal
> disk installations work perfectly under testing, however I have found a
> snag with RAID installations we have to support that were setup under grub
> legacy, which we installed under metadata 0.90 because of the limitations
> of grub legacy.
>
> The problem appears to be this bug: http://savannah.gnu.org/bugs/?34250
See parallel thread for heuristics. However note that this setup is 
fundamentally broken
> It effects RAID setups that only use a single partition per disk, and in
> my tests I got errors from grub-install of this kind:
> http://frugalware.org/paste/13418
>
> The problem seems to be that grub2 is unable to deduce *where* the RAID
> really is.
>
> I tried installing to the MBR of both disks and RAID device, using a
> simple grub-install command. (grub-install /dev/md0, etc.) I did my
> testing with a mostly vanilla 1.99 grub2.
>
> If any of our users happen to run into this issue, what are we to tell
> them to do? I'd like another option than forcing them to have to redo
> their RAID setup.
>
> Any insights would be appreciated.
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

Re: grub legacy to grub2 upgrade path

[Jordan Uggla]

2012/2/22 Vladimir 'φ-coder/phcoder' Serbinenko <phcoder@gmail.com>:
>
> See parallel thread for heuristics. However note that this setup is
> fundamentally broken

To make it easier to find, said thread is available here:
http://lists.gnu.org/archive/html/grub-devel/2012-02/msg00003.html

And ryuo, I assume that phcoder's recent request there for testing of
a patch for this applies to you as well.

-- 
Jordan Uggla (Jordan_U on irc.freenode.net)

Re: grub legacy to grub2 upgrade path

[ryuo]

> And ryuo, I assume that phcoder's recent request there for testing of
> a patch for this applies to you as well.

Interesting patch, but I realize now grub2 isn't the one at fault. The
problem is in an innate flaw in the 0.90 metadata. Even mdadm can get
confused. This happens if I try to setup the RAID with its UUID. I did
find a potential conversion method by telling mdadm to zero out the old
superblock and reconstruct it using metadata version 1.0. This doesn't
have the ambiguity problem. Thanks for the help.