Boot of Dell 1750 fails with multiple SCSI drives installed

[David Watson]

Just to add more data points.  Doug White sent me email with his
configuration.  Since he had no problems with Maxtor disks it sure
seems like the IBM disks are the culprit.

> It was 2 PE1750s with two Maxtor disks with 4.9-RC[23].  Dual 2.8GHz or
> 2.4GHz Xeons I think.  Installed and built kernls on 2 of them with
> absolutely no issues.  These had the RAID card though but I disabled it in
> the BIOS.

I've also spent more time trying various combinations of drives on
my two 2600s.  One has managed to boot twice (out of maybe 10 attempts)
with all three original drives installed.  That combined with Ryan's
success with debugging turned on really makes it seem like there's some
kind of race condition with the IBM drives and the FreeBSD mpt driver.

I've also run the Dell diagnostics on both machines with no problems showing
up.

David