Trouble migrating from IDE to SCSI drive in grub.

[Mikkel L. Ellertson]

Walter Francis wrote:
> On Sun, 15 Jan 2006 23:38:12 -0600, "Mikkel L. Ellertson" <mikkel at infinity-ltd.com> wrote:
> 
> 
>>The problem is probably BIOS mapping. When you tell the BIOS to boot
>>off the SCSI drive, then the SCSI drive becomes (hd0) instead of
>>(hd3). So Grub is trying to load from the wrong drive.
> 
> 
> Agreed, there is an inconsistancy in the bios mapping and Linux's mapping, in Linux grub-install
> --recheck shows /dev/sda is hd3, but I can edit the command line from the old IDE drive's grub
> to boot from hd2 and it boots the scsi drive.  So from the BIOS it's hd2.
> 
> But still, I can't seem to get grub on the sda drive.  I've tried numerous things, but it
> just stalls before it'd show it's loading the grub stages.  I'm at least assuming I can't get
> grub installed, it might be the BIOS isn't loading the MBR from it for some reason.
> 
> Motherboard is a MSI Ksomething Platinum with AMD64, so it's a pretty new motherboard, I don't
> think it would have issues booting from scsi.
> 
> Did I misunderstand you?  Any other suggestions?
> 
Yes, I think you did. When you change the boot device, ether in the
BIOS or by selecting the drive to boot from from the BIOS boot menu,
the drive you select becomes (hd0) in the BIOS mapping. Because Grub
has to use BIOS mapping to load the second stage, you have to make
your Grub configuration match what Grub will see when you boot.

The problem is not that Linux and the BIOS do not agree on the
mapping - it is that the mapping changes depending on how you
boot. Part of this is so that you can boot pre-XP versions of
windows by selecting the boot drive - Older versions of Windows
had to boot from the first hard drive.

Mikkel
-- 

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