[9395] in linux-scsi channel archive
Re: shared SCSI buses
daemon@ATHENA.MIT.EDU (Bill Collins)
Mon Aug 14 16:42:37 2000
Date: Mon, 14 Aug 2000 14:35:19 -0600 (MDT)
From: "Bill Collins" <wpcolli@sandia.gov>
To: "Dan Jones" <djones@valinux.com>
cc: "Kurt Garloff" <garloff@suse.de>,
"David Teigland" <teigland@sistina.com>,
"Mark Veteikis" <mark@iphase.com>,
"Chris Meadors" <clubneon@hereintown.net>,
"Martin Peschke" <peschke@fh-brandenburg.de>,
linux-scsi@vger.rutgers.edu, gfs-devel@sistina.com
In-Reply-To: <39981FAC.E45721A6@valinux.com>
Message-ID: <Pine.SOL.4.05.10008141421250.2621-100000@sass2698c.sandia.gov>
MIME-Version: 1.0
Content-Type: text/plain;
charset=us-ascii
Content-Transfer-Encoding: 7bit
A company I fondly worked for published technical journals which included
an article on this subject, http://www.digital.com/DTJR01/DTJR01HM.HTM. :-)
Those who still have their collection can refer to "Digital Technical
Journal", Vol 9 No 3, 1997.
Bill
On Mon, 14 Aug 2000, Dan Jones wrote:
> There is electrical and then there is electrical. In theory, it is a
> bad idea to remove or add a SCSI device while a transfer is taking
> place. Why? Basically, the capacitive load on the SCSI bus changes
> when drive contacts are made or broken i.e. the transmission line
> characteristics of the bus change and that affects the signal in
> flight. Since transfers during the data phase are only protected by
> parity, undetectable errors might occur.
>
> Having said that, empirical evidence points to this type of failure
> being exceedingly rare for older versions of SCSI with restricted
> configurations and qualified components. Personally, I take
> the approach that something I can't prove won't happen...can happen
> and most likely will.
>
> Some people take the opposite view and they are mostly happy most of
> the time. :)
>
> [ ... ]
--------------------------------------
William Collins
Department 04618, Scientific Computing
880/D10E1, (505)844-9414
wpcolli@sandia.gov
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.rutgers.edu
