[linux-help] FW: PROBLEM: SCSI resets w/ Tekram DC-390F and sym53c8xx driver

["Dale W Hodge" <dwh@xxxxxxxxxxxxxxxx>]

> Behalf Of Jonathan Hall
> Sent: Tuesday, July 18, 2000 10:54 PM
> To: linux-help@xxxxxxxxx
> Subject: [linux-help] Re: SCSI problems
>
>
> Termination is not the problem, as all the other SCSI devices work...
>
> Still, I have tried playing with the termination... and it's had no effect.
>
> I've also verified that no two devices are sharing a SCSI ID.

I've been watching the scsi mailing list, and there are some real problems with
cheap scsi cable/adapters and SCA devices.

Below is a message that addresses the problem.

--dwh

-----Original Message-----
From: owner-linux-scsi@xxxxxxxxxxxxxxxx
[mailto:owner-linux-scsi@xxxxxxxxxxxxxxxx] On Behalf Of Brian Leeper
Sent: Tuesday, May 16, 2000 10:17 PM
To: Robert Johannes
Cc: linux-scsi@xxxxxxxxxxxxxxxx
Subject: Re: PROBLEM: SCSI resets w/ Tekram DC-390F and sym53c8xx driver


On Tue, 16 May 2000, Robert Johannes wrote:

> I've had similar problems with that controller, with sca converters.  I'm
> using seagate (ST39171WC).  I must have gone through a dozen SCA
> connectors BEFORE I found one that seemed to eliminate the problem.  In my

Thanks for the suggestion--I got a Kingston "Single Connect Adaptor Board"
(part number DX100-SWC) that has only a wide 68-pin connector and the
80-pin SCA connector (this is the same Kingston that makes memory and
network cards).

It works perfectly. Not a single problem thus far, and I've written
roughly a gig of data to the drive since I got it installed 5 minutes ago
(it's running at the full 20MHz).

> This just leads me to think that the quality of the SCA adapters is
> absolutely critical, but the problems that they all look pretty much the
> same, it is hard to conclude which one is better.

Well, upon close inspection there are some differences:

The generic SCA adaptor does NOT supply termpower. The Kingston SCA
adaptor does (check for a termpower jumper).

The generic SCA adaptor does NOT have a multilayer circuit board with a
ground plane (to tell, hold it up to the light--if you can't see light
through the board, there's most likely a ground plane in the way). The
Kingston SCA adaptor does. In fact, the circuit board on the Kingston
adaptor is nearly twice as thick as the one on the generic adaptor, so
there's several layers in it. There are no visible traces between the
power connector and the SCA connector, for example.

The generic SCA adaptor does NOT have a capacitor or diode. The Kingston
SCA adaptor does, capacitor is probably for filtering and the diode is for
termpower.

So, look for the following when buying an SCA adaptor:

Termpower jumper. Capacitors/diodes. Circuit board that you can't see
light through.

I hope this information is useful,

Brian



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