On Mon, 11 Feb 2002, Tothwolf wrote:
> On Mon, 11 Feb 2002, Geoff Reed wrote:
> > At 12:34 PM 2/11/02 +0000, you wrote:
> >
> > >SCSI Wide also supports plain old SCSI devices. I'm running such a
> > >configuration in my web server (3 SCSI Wide drives and 2 SCSI-2)
> >
> > Yup, sellam's right, be warned however that your SCSI bus will be hobbled
> > to the speed of the slowest device usually.
>
> Right. I'd certainly not mix wide and narrow devices on one channel.
> Termination of the bus is also often a pain when you do this.
It wasn't much of a problem for me. I'm using an Adaptec 2940UW (or is it
a 2940W?) and it has both SCSI and SCSI Wide connectors on the card
internally, and a connector on the back that may or may not be SCSI Wide.
I think either you specify in the card's BIOS setup whether you want
to use the internal connectors or a combination of one of the internal
connectors and the external connector, or it auto-detects (I haven't
played with it in a long time, but I know at one point I had a Syquest EZ
Flyer attached to the external connector along with the internal SCSI Wide
drives). If you attach drives to all three, you get problems (I know this
from experience ;)
So you just terminate each device at the end of whatever chains you use.
If you use the internal SCSI and SCSI Wide chains, you terminate the last
SCSI device and the last SCSI Wide device. If you use the external
connector, apply termination to the last device on the external chain and
the last device on the internal chain. It works perfectly.
> What can't be done, is put 15 narrow devices on one wide channel. Well,
> at least and have them all work anyway.
Narrow devices are only able to address up to SCSI ID 7 as far as I know
(otherwise they'd be SCSI Wide devices). Only Wide devices know that
devices IDs from 8-15 exist.
Sellam Ismail Vintage Computer Festival
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Received on Mon Feb 11 2002 - 08:46:21 GMT