[dm-devel] Re: grub 0.96 bug

[Molle Bestefich]

Wilfried Weissmann wrote:
>> It must be severely broken; since if it just sticked to writing to the
>> device I pointed it at (hpt37x_ehgjaggaf) which is a RAID0 "virtual
>> disk" / whatever, it should never be able to overwrite metadata out on
>> the physical disk.
> 
> HPT desided to make the metadata accessable from the virtual disk. Just
> look at sector 9 of a working array and enjoy the show...

That's an awful decision.

> Grub is fine. At least the version that I am using. You have to do some
> tricks to get grub running on the old hpt controllers (I think the new
> ones are better, but I cannot tell for sure).
> 
> Just copy the stage 1.5 reiserfs module to sector 16 instead of sector 8
> which is the grub default that destroys the metadata in case of a hpt.
> [explanation snipped]

Thanks for the explanation!
There should be an option in the GRUB configuration to do this, so
that the RAID won't get overwritten the next time I do a grub-install,
I think.

Or even better, dmraid could protect the metadata blocks by some magic
flag to dm-mod.
This isn't possible as is, is it?


>> Gerte has a GRUB example on his page where he does setup (hd0,5)
>> instead of setup (hd0), perhaps that's how it's meant to work.
> 
> But you still need a MBR that invokes the loader in (hd0,5) then!

Hrm, I think LILO has an option to slam out a generic MBR that does
something like that?
But perhaps it requires an active flag on (hd0,5), which violates the specs..