Subject: Re: scsi id #'s vs. driver id's
To: Armen Babikyan <armenb@moof.ai.mit.edu>
From: Bill Studenmund <wrstuden@loki.stanford.edu>
List: port-mac68k
Date: 09/03/1997 10:35:03
> i don't know if this question is port-mac68k specific, but why does NetBSD
> use it's own driver scheme, rather than Linux's, where the number in the
> device driver would correspond to the SCSI ID?
> 
> i have 3 netbsd disks, SCSI ID's #0, 2, and 3. when all powered up, NetBSD
> sees them as /dev/sd0, sd2 and sd3, respectively.

Shouldn't that have been sd0, sd1, and sd2? Or is there an sd1 which is
just for MacOS.

> sometimes i shut off disk ID #2 because i don't need it, but that's not
> cool with /etc/fstab, which wants to now see the SCSI ID #3 drive as
> /dev/sd2
> 
> i like linux's number scheme better.  why doesn't netbsd do that?

As others have mentioned, this scheme is more flexable w/ lots of
drives and with many scsi busses. Basically to hard wire, you'd have to
wire down each possable drive on each possable bus. For mac68k, it doesn't
matter much as we only really support one scsi bus. But for other ports
(like i386), you can have multiple kinds of scsi cards (BT, NCR, and 
Adaptec for example). So if you booted a generic or an install kernel,
your one hard disk might be sd16 (assuming your controller was the third
one listed and they all supported only 8 targets).

But what happens when a controller can support 16 targets?

I have a suspicion you'll get used to it. If you check the archives
(and they go back that far) you'll find one of my first posts
complained about the very same thing!

Take care,

Bill