IDE controllers

[Alex Pournelle]

root at crash.cts.com (Bill Blue) writes:

>In <1990Nov21.093114.15468 at grian.cps.altadena.ca.us> alex at grian.cps.altadena.ca.us (Alex Pournelle) writes:

>I too speak from experience.  The problem with IDE drives and Xenix is
>not the drive or the controller ON the drive.  It is with the adapter
>card that plugs into the motherboard and connects to the drive.

I'll have to come down on the other side of this one, Bill.  The Conner
people I've talked to, the SCO people, the third-parties who've send me
info on this--everyone else agrees that it's the drive, and almost the
drive alone, that determine the gotchas in most systems.

The adapter board's important for *some BIOSes*, no question.  Don't run
an IDE drive with an AMI BIOS dated before 12/15/89; AMI did a major fix
of their drive-handling code.  Previously, you'd have to use the "Conner
Compatibility jumper" on that adapter board--in other words, set for
IRQ14 buffered--to keep from getting oddball drive not ready errors.
This cures that.

Conner themselves, though not directly, admit that the 3104 has a
problem with asserting data-ready before it really was.  This may be
fixed in latest release, but who can tell from firmware?  At the moment,
what I have is a repeatable crash.  Yes, it gets worse when I switch IDE
adapter boards--from the ``no name'' Taiwan to the ``brand name''
Western Digital.  Yes, that's right: the WD-240 is WORSE than Joe's
Taiwan Clone & Bottle Company.  Both crash in 6<x<24 hours.

>Using good adapter boards, I have installed quite a number of Xenix
>systems on IDE drives with no problems.  In fact I use a Conner CP3104
>on one of my test systems day in and day out.  IDE drives are
>basically RLL and you can expect the same general performance and data
>throughput as you would with any other quality RLL drive/controller
>combination.

Well, "basically RLL" is a major misnomer.  You've seen my postings for
long enough to know that I wouldn't use an RLL ANYTHING in a production
machine--too risky.  But, we all know that the embedded controllers on
very advanced drives used embedded servo-tracking to `watch over' the
data's viability: they do a good job of ensuring you'll get back what
you put on.  Using an RLL controller & drive is putting 15 pounds into a
10 pound sock, and I don't think it's reliable enough.

My 2 quatloos' worth.  Glad you get it working: perhaps this SLS 133
will fix me up, too.

	Alex
-- 
		Alex Pournelle, freelance thinker
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