On Mon, 11 Feb 2002, Jeff Hellige wrote:
> > > But as you pointed out, it will slow it down. My boot hard
> >> disk is a wide SCSI drive, so I'd just as soon not have it drop back
> >> to the SCSI-2 speed of the interface for my scanner, which is an
> >> older Relisys Infinity Scorpio. I also use the narrow interface for
> >> checking out smaller (40MB-1GB) SCSI hard disks that I pick up.
> >
> >A narrow device *will not* slow down a wide bus.
>
> Ok, you're telling me that if I have:
>
> - a wide SCSI adapter, such as an Adapter 2940U2B, running at
> 40mhz and I have the adapter set to SCSI ID# 7
> - a wide SCSI hard disk, such as an IBM DDRS-39130D, set at
> SCSI ID# 0 and also running at 40mhz
>
> The above settings are the default ID# for the 2940U2B and
> ID# 0 is the factory default for the boot drive on the Macintosh both
> are installed in. 15 total SCSI ID#'s available on the 2940U2B.
>
> That if I add a narrow SCSI hard disk, take your pick,
> running at the fast-SCSI rate of 10mhz, that it won't slow the wide
> SCSI bus down? That goes contrary to what I've seen and I've seen
> plenty of narrow drives have a problem running on a bus that much
> faster. That's why Adaptec's PowerDomain Control software allows you
> to manually tailor the bus speed to try and find a happy medium for
> all the devices you have on the bus.
You're adding another variable. You're adding a disk at *10MHz*. If you
add a narrow disk at *40MHz* then it won't slow down the SCSI bus.
Peace... Sridhar
> I'm not trying to be argumentative, but if I'm
> misunderstanding something, and have been for quite a long time if
> that's the case, I'd like to be corrected.
>
> Jeff
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>
Received on Mon Feb 11 2002 - 19:48:28 GMT