Hmm,
I can't really remember the proper explanation (sorry), I think that you
will find that this is based on a half truth.
In your example, if you used two devices of the same connection type, but
different speed there should be no slowdown.
SCSI typically uses a 32bit processor which can submit commands and
disconnect from the devices and uses other things such as tag queuing to
limit any possible performance hit.
You will have this problem, however if use a LVD & SE device on the same
channel, but this is a different scenario.

Thank You 
Brett Olsen 


-----Original Message-----
From: Michael Lake [mailto:[EMAIL PROTECTED]] 
Sent: Wednesday, 16 October 2002 2:02 PM
To: SLUG Mailing List
Subject: Re: [SLUG] Repair shop?


Graeme Robinson wrote:
> 
> On Wed, 16 Oct 2002, Voytek Eymont wrote:
> 
> > on a perhaps related issue, I have been told it's a 'bad idea' to 
> > have a slow device such as a scanner on one SCSI buss, as, it will 
> > bring the whole SCSI chain to the lowest common speed.
> 
> I've never had a problem sharing a scanner with a cd burner on one 
> chain. Both have run reliably on it for years.
> 
> That's what SCSI is all about - fast reliable bus sharing - and is 
> probably why it's been around for so long.  I've never even heard of 
> devices interfering with each other on a scsi chain, unless they try 
> to grab the same ID.

I have just got myself a new Tekram SCSI controller and it certainly
mentions to avoid having a slow UltaFast device on the same channel as newer
160MB/sexs channel. It provides two channels on the same controller so you
can separate them otherwise its says it will drop its speed to match the
slowest.

Mike
-- 
Mike Lake
Uni of Technol., Sydney


UTS CRICOS Provider Code:  00099F

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