[2482] in linux-scsi channel archive
Re: Problems with AHA2940AU
daemon@ATHENA.MIT.EDU (Tom Goltz)
Wed Sep 17 21:02:21 1997
Date: Wed, 17 Sep 1997 21:04:19 -0400
To: =?iso-8859-1?Q?=22R=2EO=2E_Bl=E4ttner=22?= <rolf.blaettner@nuernberg.netsurf.de>
From: Tom Goltz <tgoltz@mediaone.net>
Cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <341FF26A.36CAEAF6@nuernberg.netsurf.de>
At 05:08 PM 9/17/97 +0200, R.O. Blättner wrote:
>(3) Now, my MISTAKE:
>
> I'd TWISTED the ID connector at one of the disks !
>
>Thusly, I'd shortened the disk's ID bit pins by the "black row" of the
>cable connector and, vice versa, connected the disk's "ground pin row"
>to the cable connector's "colored" coding bit row ... :-([
>
> @!<^!&=~!# GRRRrrrrrrrrrrrrrrrrrrrrrmpf !! Aaaargghhhhh !!
> (Should read as all evil cursed words You ever may remember)
>
>The results of this ugly twist I never could realize exactly until now,
>because sometimes it worked, othertimes it didn't.
>... must either depend on the time sequence of accessses to the various
>devices, or on voltage levels, the temperature, the moon phase, or the
>number of black holes in the Milky Way ...? :-) DUNNO
An excellent story, and well-worth noting. I doubt it applies in my case,
since all three devices are internal, with the SCSI address being set via
jumpers. I have also run the adapter BIOS setup and scanned the SCSI bus
and verified the addresses of all three devices.
As I have learned the hard way, anytime someone says SCSI (and ESPECIALLY
ULTRA), the number one question has to be termination. I have seen MANY a
freaky SCSI problem due entirely to improper termination.
Sadly, in this case I'm pretty confident - it's a short internal-only
50-pin ribbon cable, with the terminator enabled on the Ultra-SCSI hard
drive, and the drive has been configured to supply termination power as
well. The other terminator is in the controller. I think it's a pretty
safe bet that both of these are adequate for Ultra-SCSI operation.
It is interesting, but not conclusive that the erase operation completes
flawlessly when I pull the AHA2940U and install a AHA1542CF instead. This
is a much lower-performance controller, unfortunately.
-----
On a SCSI, but not Linux issue, per se, has anyone come up with a solution
that allows the use of an external SCSI Iomega ZIP drive on a SCSI chain
running at Ultra speeds? The controller likes to hang anytime the ZIP
drive is connected unless I force 10mb operation on all devices. I'm about
ready to see just how many pieces you can get from a ZIP drive!
Tom Goltz
Software Engineering Services
(508) 863-1175
tgoltz@computer.org
