> 
> On Sun, 21 Dec 1997, Armen Babikyan wrote:
> 
> > NetBSD/mac68k (and maybe NetBSD in general) does not assign device numbers
> > based on SCSI ID, just by order they come in on a SCSI chain. for
> > instance, a NetBSD box with root partition SCSI ID #4 would be mounted as
> > /dev/sd0, but if a drive with SCSI ID #2 was added, the new drive would be
> > /dev/sd0, and the #4 would be /dev/sd1. similarly, your cd drive would be
> > /dev/cd0, no matter what SCSI ID it is, because you only have 1 CD drive
> > attached.
> > 
> > The only use of this "feature" (that I can see) would be to be able to
> > boot a NetBSD machine without having to know or assign what drive is
> > on what device number, as labeled in /etc/fstab on linux systems; the
> > machine just mounts the first numbered SCSI device it comes on in the
> > chain (which is, on many macs, 0).
> 
> Perhaps there needs to be some clarification here...
> 
> Linux's /etc/fstab does not do anything more than any other unices'
> /etc/fstab.  It does NOT map dev entries to SCSI nexxus/addresse points.
> 
> Linux's /dev/sda can be ID0 or ID5 or whatever...their assigned in the
> order drives are found on the bus.    SImiliarly, my SCSI cdrom on ID3 is
> named /dev/scd0, which has nothing to do with the fstab.
> 
> You may be thinking of something that some BSD-based commercial unixes do.
> Such as Ultrix:  the devices are named /dev/rz{ID} or /dev/rrz{ID} where
> ID is the SCSI ID.   

Right. Older BSD unixes had the ID's hard coded. The fact that NetBSD
doesn't seems weird at first. In fact, if you search the archives,
you'll find some complaints about that from me from many years ago.

Once you get used to it, it's not that bad. And it certainly adds
flexability. The real advantage comes if you boot a computer with
multiple scsi busses. It's rare with mac68k's, but true for docked
duo's (I think). This way, you don't have to hard-code two scsi busses
worth of ID's.

Also, if you have the space to compile your own kernels, you're
supposed to once you get installed. Basically just go in and
hard code the scsi disks where your disks live. Then you won't
have things changing number on you.

Remember, the GENERIC kernel is designed to work on most any
computer.

Take care,

Bill