dell 6850 with PERC 4e/di boot from third logical disk problem

Ben Scott dragonhawk at gmail.com
Thu Dec 28 19:21:48 CST 2006


On 12/28/06, mcclnx mcc <mcclnx at yahoo.com.tw> wrote:
> It still boot from first disk instead of third disk
> (supposely after "boot drive" set to 2, third disk
> will be /dev/sda and first disk will be /dev/sdc).

  I've never tried what you're doing precisely, but in many cases,
changing the BIOS boot drive will only affect software that uses the
BIOS (i.e., LILO, GRUB).  The kernel does not know or care about the
BIOS boot drive designation.  (There are exceptions, but I don't
understand them well enough to explain them.)  So the kernel is still
going to be mounting the same root partition.

  To fix this, I think you would need to make two boot loader entries,
with different kernel boot= arguments, but the same boot loader kernel
file configuration.  For example, with GRUB, you would have:

title First logical disk
root (hd0,0)
kernel /vmlinuz-1.2.3 ro root=/dev/sda

title Third logical disk
root (hd0,0)
kernel /vmlinuz-1.2.3 ro root=/dev/sdc

  GRUB uses the BIOS, so changing the BIOS boot disk will make the
third logical disk appear as the first, hence "root (hd0,0)" for both.
 But the kernel ignores the BIOS, hence different "root=" arguments.

  DISCLAIMER: I've never tried this.

-- Ben



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