[8530] in linux-scsi channel archive
Re: Fast Wide vs Ultra Wide
daemon@ATHENA.MIT.EDU (Matthew Dharm)
Tue Apr 4 01:32:44 2000
Date: Mon, 3 Apr 2000 22:31:11 -0700 (PDT)
From: Matthew Dharm <mdharm-scsi@one-eyed-alien.net>
To: Ricky Beam <jfbeam@bluetopia.net>
Cc: The Linux SCSI list <linux-scsi@vger.rutgers.edu>
In-Reply-To: <Pine.LNX.4.04.10004040046580.23096-100000@beaker>
Message-ID: <Pine.LNX.4.10.10004032229270.32219-100000@ziggy.one-eyed-alien.net>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
On Tue, 4 Apr 2000, Ricky Beam wrote:
> Are the drives jumpered for parity? If they aren't jumpered, they may not
> even calculate parity.
No parity jumpers.
> >with a device plugged in. No combinations of just cables and terminators
> >will cause this to happen.
>
> Pardon my "attitude", but _duh_. If there's nothing to talk to, where's
> it supposed to get a parity error? The terminator is just a bunch of
> resistors. Here's how this works... the initiator (scsi card) sends a
> command and data to the target (drive). The target calculates parity
> for what it received and checks it against what it should see. If it
> detects a parity error, it signals an error to the initiator (check condition
> with sense data indicating a parity error.) The initiator does the same
> check in receiving data back from the target. The parity information is
> "out of band". It's in parallel to the data on the bus -- 8bit data, 1bit
> parity -- and thus can be processed "on the fly".
Good. This means that I'm not crazy.
The thing that got me is thi: the test that the controller performs is
independent of devices. In fact, it's under a heading marked "cable
tests", and there is a separate section for "device tests". I didn't
think parity was in-band data...
So it looks like this controller is isolating me too much. I think it's
time to invest a bit more money into this problem and get a new controller
to test with
Matt Dharm
--
Matthew Dharm Home: mdharm@one-eyed-alien.net
Engineer, Qualcomm, Inc. Work: mdharm@qualcomm.com
E: You run this ship with Windows?! YOU IDIOT!
L: Give me a break, it came bundled with the computer!
-- ESR and Lan Solaris
User Friendly, 12/8/1998
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