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Date:	Tue, 3 Dec 2002 23:49:59 PST7
From:	Steve Carter <scarter@vcnet.com >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: Adding a second SCSI adapter

Content Type: text/plain

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The wide-to-narrow transition that occurs somewhere between the external
wide 68-pin connector of the [Symbios] host adapter and the narrow 50-pin
connector of the HP5 is problematical. It can leave a number of signals
un-terminated, causing uncertain behavior.

Often you can specify SCSI bus characteristics on a target-by-target basis.
The scanner is the slowest common SCSI device I know of. Faster speeds do
it no good.

External devices are often slow, by their very nature. The additional
length of the external SCSI cable necessitates slower bus clock
speeds be used. A second SCSI adapter (narrow and slow) is not a bad
solution, especially if you already have one.

I'd suggest Steven is likely right in his assessment of termination
as a likely culprit. Long (i.e. external) cables only exacerbate the problem.
Short, slow SCSI buses are tolerant of cabling/termination problems.
As you get farther away from short and slow, everything has to be just perfect.

++++++++++++++++++++
On 12/1/02, Steven Levine wrote, in part:
>... More worthwide would be things like
>suppressing wide negotiation and sync negotiation and dropping the bus
>speed to 5MB/s.
>
>>hangs my system if I try to boot with the HP5 attached to my main SCSI
>>adapter. My system is all SCSI: LSI Logic SYM21002 dual channel with ...
>
>When does it hang? During the BIOS bus scan or elsewhere? I'd have to
>see a connection diagram to be sure, but most often bus hangs are
>termination issues or inadvertent Y-configurations, although if I am
>visualizing your layout correctly, I'd suspect termination first.

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