[5729] in linux-scsi channel archive
RE: Adaptec 2940UW controller driver for Linux
daemon@ATHENA.MIT.EDU (Allison, Bob)
Thu Jan 28 01:10:38 1999
From: "Allison, Bob" <BOB.allison@qwest.com>
To: "'doctor@fruitbat.org'" <doctor@fruitbat.org>,
"Allison, Bob" <BOB.allison@qwest.com>
Cc: david.c.hoos.sr@ada95.com, mhuff@colltech.com,
linux-scsi@vger.rutgers.edu
Date: Thu, 28 Jan 1999 00:41:04 -0500
Well, maybe you can tell me what I did wrong.
I pulled out the 2940UW and put the 2940U2W in its place, plugging the
50-pin ribbon into the U2W exactly as it was in the UW.
When I powered up the machine, the U2W saw no devices (at the BIOS listing,
had a hard time booting from /dev/sda2).
I swapped the boards back and everything was fine (both disks, the CD, and
the tape were back).
-----Original Message-----
From: doctor@fruitbat.org [mailto:doctor@fruitbat.org]
Sent: Wednesday, January 27, 1999 3:06 PM
To: BOB.allison@qwest.com
Cc: david.c.hoos.sr@ada95.com; mhuff@colltech.com;
linux-scsi@vger.rutgers.edu
Subject: Re: Adaptec 2940UW controller driver for Linux
Allison, Bob said ...
>
> AFAIK, the 274x/284x/294x driver in Linux supports all of the 294x family,
> including the 2940U2W (at least, it was recognized on my system).
>
> The 2940U2W uses UltraSCSI signal levels (LVD=Low Voltage Differential).
> Although the documentation indicates that it can drive single-ended as
well
> as differential devices, I found that it would not drive my older SCSI-2
> drives. This is because they require a higher signal voltage.
Untrue. The controller has a fall back mode in which it will switch to
SCSI-II signal levels to support non-LVD devices on the U2 bus. However,
mixing LVD and non-LVD on the same bus will reduce the through-put to
SCSI-II levels. I've a mix of devices on the LVD bus and this is the
results I get. Perhaps you didn't have proper termination?
> Unless you have LVD devices, you better stick to the 2940UW for SE devices
> and 2944UW for FWD devices.
Na. The 2940U2W does quite well for either.
--
Peter A. Castro (doctor@fruitbat.org) or (pcastro@us.oracle.com)
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