Re: Need help - lost access to my NetBSD partitions

[Ignatios Souvatzis <is%netbsd.org@localhost>]

On Wed, Jan 30, 2002 at 05:16:27PM +0100, Gunther Nikl wrote:
> 
>   Well, I don't know if thats really true but it sounds logical: If you want
>   to use narrow and wide devices on the same hostadapter you can't use any
>   wide ids because the narrow devices won't recognize the wide id. The
>   narrow device might think the request is targeted for its id but really
>   its for the wide id.

Fortunately, thats wrong. Targets on the parallel SCSI busses are addressed by
a bitmask.
A narrow device simply won't see a target ID >= 8, and not react. (I've never
seen a 32bit SCSI bus, but it is supposed to exist, and a 8- or 16bit device
will never feel addressed by an target id >= 16.)

The advice to use >=8 for wide targets is so that the ids <7 stay reserved for
the narrow targets that can't use the ids >=8. Both can happily talk to the
wide scsi host adapter, if it uses an id <= 7 (in violating the above rule
of thumb). (Normally, our disks don't talk directly to other disks.)

Regards,
        -is