Subject: Booting sd0 (disk geometry versus bios geometry)
To: None <port-i386@NetBSD.ORG>
From: Anders Dinsen <dinsen@danbbs.dk>
List: port-i386
Date: 06/18/1998 21:57:11
Greetings,
I just got a 400 MB SCSI disk in my system, which I for several
reasons would like to boot from instead of the IDE disks I also have
(see my other post about sd vs. hd performance).

Its on an AHA1540B. I have enabled the BIOS, and it finds the disk all
right. But the system reports 'missing operating system' when it tries
to load the NetBSD boot loader. I _can_ load the boot loader from wd0
or diskette and boot netbsd-kernel with hd1a:netbsd.

The disk has more than 1024 cylinders, so I assume the problem has
something to do with that. I disklabeled it with the sysinst program,
and it asked me if I wanted to use the real geometry or any other. I
chose to use the real geometry.

Is it the AHA BIOS that changes the geometry so the disk has less than
1024 cylinders, and the disklabel (and boot loader) I wrote is placed
in a way on the disk so that it cannot be loaded?

If so, which geometry should I use for disklabelling? Or: How can I
determine the logical geometry that the AHA BIOS reports?

Regards,
Anders