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From: steve@gec-mi-at.co.uk (Steve Lademann)
Newsgroups: net.unix-wizards,net.bugs.4bsd
Subject: Re: Possible uda50 driver problem
Message-ID: <194@miduet.gec-mi-at.co.uk>
Date: Mon, 1-Sep-86 09:46:19 EDT
Article-I.D.: miduet.194
Posted: Mon Sep  1 09:46:19 1986
Date-Received: Tue, 2-Sep-86 21:27:42 EDT
References: <189@miduet.gec-mi-at.co.uk> <3151@umcp-cs.UUCP>
Reply-To: steve@gec-mi-at.co.uk (Steve Lademann)
Organization: Marconi Instruments Ltd., St. Albans, Herts, UK
Lines: 47
Xref: mnetor net.unix-wizards:7747 net.bugs.4bsd:908

Chris,
	Many thanks for input on my uda50 problems. The state at
present is that my annual holiday just happened to coincide with
a visit of our service engineer with a replacement memory controller
and the re-instatement of the original 4.2BSD driver. The problem has not
recurred, so one or the other fixed it. The next problem is to find
sufficient time to isolate the actual cause....

I would be most willing to act as a beta site for your driver, apart
from 2 problems which I believe to be common in this lesser part of
the world called Europe. These are :-

1)	4.3 BSD is not available yet in Europe due to legal problems
	somewhere in U.S. governmental bureaucracy or in University of
	California. (Actual reasons for non-availability seem to vary
	depending on who you speak to - does anyone *really* know?)

2)	I find that large volumes of data are extremely tricky to get
	across the Pond when you are a commercial organisation,
	especially from academic sources. Is this because I don't know
	the right people? (Comments, uk contacts, etc. *very* welcome, 
	especially Arpanet, or whatever it's called nowadays :-)
	I tend to resort to mag. tapes and things in the end. E-mail
	is restricted to 1200 baud PSS or 300 baud dial-up.

With regard to bad block replacement, yes, I would agree that the 
replacement of bad blocks with a separate process makes a lot of
sense. It hopefully reduces the complexity (and hence potential bugginess)
of the driver. However, from what I've seen with regard to the bad block
replacement algorithms, there is a lot of Black Magic involved in the
process anyway. I went through a period of rapid change with regard to HDAs
on our RA81 before they found one which had non-destructive glue (yes, they
put one of the old ones in which had to be changed *again* before it got
its act together!) and this prompted me to do something about the driver.
What will your solution to the problem of getting rid of bad blocks be
(if any)? I must admit that after your comments with regard to the 'iffy'
algorithm in the RIACS driver, mine could well be to call Field Service!

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|Steve Lademann         |Phone: 44 727 59292 x326               |
|Marconi Instruments Ltd|UUCP : ...mcvax!ukc!hrc63!miduet!steve |
|St. Albans    AL4 0JN  |NRS  : steve@uk.co.gec-mi-at           |
|Herts.   UK            |                                       |
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