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Re: Unable to boot BIOS/GPT system.




quantera@xxxxxxxxx wrote:
>
>I am trying to install Debian on a 4TB external HDD. Since I want
>to boot the HDD (also) on old systems which support only BIOS,
>and since the HDD is larger than 2TB, I decided to go with GPT
>partition table and BIOS boot (or, in other words: BIOS/GTP).
>I partitioned the HDD accordingly (see the details below), and
>installed Debian. During a pre-installation configuration the
>installer recognized BIOS boot partition, I configured the root
>partition as ext4 and installed grub into the disk's MBR. But
>when (after an installation) I am trying to boot the HDD, I receive
>an error message: 'error: unknown filesystem' and drop into a
>grub rescue mode.
>
>What is the problem here and how it can be solved? It seems as
>though grub's Stage 1.5 loader (that is - core.img, which is
>supposed to be embedded in BIOS boot partition) doesn't contain
>modules needed to read ext4 filesystem, which seems very strange.

...

>Number  Start     End         Size        File system     Name  Flags
>  1      1.00MiB   2.00MiB     1.00MiB                           bios_grub
>  2      2.00MiB   16000MiB    15998MiB    linux-swap(v1)
>  3      16000MiB  3815414MiB  3799414MiB

I'd expect that Grub won't be able to reliably work with that setup -
partition 3 goes past the 2TB mark, so the BIOS won't be able to map
it properly. Don't forget, when grub is reading the disk all it can
rely on are BIOS calls. Add yourself a small-ish /boot partition first
and you may be OK.

-- 
Steve McIntyre, Cambridge, UK.                                steve@xxxxxxxxxx
"Further comment on how I feel about IBM will appear once I've worked out
 whether they're being malicious or incompetent. Capital letters are forecast."
 Matthew Garrett, http://www.livejournal.com/users/mjg59/30675.html