[Gllug] installing grub on the Mbr

Nix nix at esperi.org.uk
Thu Jan 18 00:28:58 UTC 2007


On 17 Jan 2007, Russell Howe said:

> On Tue, Jan 16, 2007 at 10:19:00AM +0000, Anthony Newman wrote:
>> I'd probably regard MBR installation as a last resort for machines which
>> won't work otherwise, as it's annoying to have to reinstate it after
>> other OSen destroy the MBR as part of a normal installation.
>
> Note that some filesystems (well, XFS at least) use the first blocks of
> the partition (most - all? - others leave the first bit alone) and as
> such, if you install a bootloader to the beginning of a partition
> containing an XFS filesystem, you overwrite the superblock.

Indeed. Combine this with Solaris disklabels (which consume no space,
such that /dev/sda and /dev/sda1 start at the same place) and pvcreate
for added extra fun.

(This is also one reason why md's superblocks are by default near the
end of the partition, and why other superblocks exist that are 4Kb in
from the partition start.)

-- 
`The serial comma, however, is correct and proper, and abandoning it will
surely lead to chaos, anarchy, rioting in the streets, the Terrorists
taking over, and possibly the complete collapse of Human Civilization.'
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