Boot disk?

[T.C. Hollingsworth]

On Sun, Dec 25, 2011 at 2:37 PM, Jeffrey Ross <jeff at bubble.org> wrote:
> Is there a way to identify which disk the BIOS is using to boot from (eg
> disk 0 or 1) when I don't have physical access to the system to view the
> BIOS settings?
>
> The situation is this, I have a machine at a remote location where the
> system runs RAID-1 and both disks (0 and 1) can boot the system, I need to
> rewrite the boot sectors on the disks and I don't have easy access to the
> machine so I have to be careful as to which order I do them.

If both disks have identical bootloaders, I'm not sure there's any way
from a running system to check which one you booted from.  If you
don't mind rebooting it, you could add a different arbitrary kernel
argument to the GRUB configuration of each disk's bootloader, reboot
the machine, then check /proc/cmdline to see which one shows up.

That being said, why does the order matter?  So long as you do both
correctly before rebooting the machine all should be well.

-T.C.