*BSD News Article 75448


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From: Michelle Brownsworth <michelle@efn.org>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Setting geometry important for SCSI disk?
Date: 5 Aug 1996 06:00:07 GMT
Organization: EFN
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I was under the impression that disk geometry was irrelevant and could 
safely be ignored when installing on a large SCSI if the entire disk was 
to be allocated to FreeBSD.  I did an FTP install on a Seagate ST-12550N 
2.1 mb SCSI drive, which is connected to a Adaptec 2940 PCI SCSI 
controller.  The geometry the sysinstall program came up with, and the 
one I used, was 2040/64/32.  As I mentioned above, the entire disk was 
dedicated to FreeBSD.  I opted to not install the boot manager, since 
there would be no sharing with other operating systems.  I accepted most 
defaults, other than increasing the root partition to 132 mb, and /usr 
to 1802. The install seemed to go smoothly.  However, when the moment of 
truth arrived--booting from the hard disk--I was greeted with "Missing 
Operating System."

Boot:  sd(0,a)/kernel will boot kernel on the SCSI, but we need it to 
auto-boot, for obvious reasons.  At least I do have access to pfdisk to 
use for detective work if I need it.

This is my first foray into installing FreeBSD on a large SCSI.  I 
thought it would be easier than IDE, but that doesn't appear to be the 
case; the IDE seemed easier.  If I remember correctly I used the 
translated cyls, trks, and secs provided by the BIOS config in the 
FreeBSD install program to setup the drive geometry.  (But in that 
installation I also used the first 528K (1024 cyls) for a DOS partition 
and installed the boot manager.)   This time out, the BIOS config is not 
giving up any drive info, translated or otherwise, because the Award 
BIOS doesn't even seem to detect the SCSI drive. The drive setup in the 
BIOS Config program seemed to refer to IDE drives only, so I left it 
alone, with no information--all zeros--for cylinder, track, and head 
info.  I suspect this is where I went wrong, if indeed the BIOS is 
instrumental in booting the kernel, but I don't know how to fix it.  
Perhaps pfdisk?

I've read a FAQ citing the same missing OS message that indicated it was 
caused by a geometry problem, and another that alluded to keeping the 
drive in "native" mode (not sure what this means), and making sure the 
root partition is below 1024 cylinders so the BIOS can boot the kernel 
from it.  Certainly, this is the case in my installation, is it not so?

But I swear I read where Jordan or J"org maintained that, if the entire 
disk is dedicated to FreeBSD, geometry can be pretty much ignored...

[scratching head]
\\ichelle