[wellylug] Grub doesn't like LBA mode

[David Antliff]

On Sat, 23 Oct 2004, Bill Christiansen wrote:
> I wondered why whenever I installed a distro that used grub on one of my
> pc's I would get a grub error 18 when I rebooted. My usual work around
> was to replace the grub with lilo and that worked fine, however I just
> discovered that if I change the hard drive mode in the bios from LBA to
> normal then grub will also work fine. I was also surprised that I didn't
> loose any data when I did this (I guess it just re-assigns logical
> cylinders and heads on the drive). Not sure why grub is more fussy about
> this than lilo.

My understanding is that once Linux boots, it takes over the disks and 
uses it's own methods. The BIOS disk settings are just to get it booting 
(i.e. find the MBR). You don't even need to specify a (non-booting) HDD in 
the BIOS for Linux to use it. This has the consequence that you cannot 
disable a drive in the BIOS to prevent a modern OS from seeing it, in my 
experience at least.

As for why GRUB is fussy, I'm not really sure.

-- 
David