a hardware question

[David P. Schwartz]

I picked up an IBM 8650-4MO (Model 704) computer at an auction a while
back.  This is an x86-based system that can have up to 4 CPUs and a wad of
SCSI drives.  It's got two Adaptec UltraSCSI-II channels on the main board,
and it also has an IBM ServeRAID controller that supports three separate
UltraSCSI-II channels.

We're trying to install Debian onto a 4.3 GB drive.  There are a couple of
36GB drives configured as a mirrored pair.

The problem is that the silly ServeRAID card seems to override the main BIOS
boot selections!  We could never get it to boot from the floppy (booting
from a DOS-based IDE HDD show that the floppy drive and controller logic is
fine).  The system will boot from a local IDE HDD, but booting from a SCSI
drive seems to have happened only as an accident.

The machine goes through the POST, then stops with an advisory, "Please
install a bootable disk in the appropriate drive".  The problem is, we can't
figure out which freak'n drive it's looking at!  (The "appropriate" one,
obviously!)  It doesn't matter what boot source you set the main BIOS to, it
just keeps doing the same thing.

Is there anybody here who's familiar with these particular systems, or who's
seen similar behavior on other SCSI-based machines, and might have some
suggestions?

Thanks
-David