Path: utzoo!attcan!uunet!decwrl!elroy.jpl.nasa.gov!grian!alex
From: alex@grian.cps.altadena.ca.us (Alex Pournelle)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Follow up to hard disk autoparking and a SCSI question...
Message-ID: <1990Jun28.092451.10054@grian.cps.altadena.ca.us>
Date: 28 Jun 90 09:24:51 GMT
References: <1990May31.051839.23825@athena.mit.edu> <8823@goofy.Apple.COM>
Organization: Workman & Associates
Lines: 67

Perhaps more about this subject than you wanted to know, but I've been a
hard week recovering from drives that were NOT properly shut down, so...
(A hazard of the data-recovery business is getting overly evangelistic,
but You Can Never Have Too Many Backups.)

RANDO@applelink.apple.com (Damon Rando) writes:

>In most newer drive 
>designs [there is a] parking mechanism that automatically parks the head stack 
>in the landing zone when power is turned off.  Apple only sells one drive 
>that still uses stepper motor technology (the 20Meg).  My understanding is 
>that the heads are parked on this drive when "Shut Down" is selected under 
>Finder (99% sure).

(1) depends on the 20, some are smarter than others.  The great majority
are MiniScribe 8425SAs, which are usually strapped to auto-park after 30
seconds (you can hear a seek operation after about that long on some
macs, and it's best to wait for it).
(2) Shut Down doesn't do it--Option Shut Down will on some models.
(3) But Apple's shutdown code doesn't always send the proper SCSI
shutdown command.  I've a pair of Priam EM330 drives (wonderful,
beautiful, great--shame about the company) which don't even offer
parking from their (terrible) driver software.  SilverLining, which has
been used on one of them, will offer to install a shutdown/spindown
vector, but it's grotty and doesn't work on these monsters.
(4) SCSI Parker, the public-domain CDEV, DOES work on jus' about
everything I have.  It's pretty scary to hear the Priams spin down (for
they interpret the command as a real shutdown) when I use "Shut Down";
the office gets real quiet.  Some 8425SAs will actually spin down,
others will just park; still others ignore the command.  MiniScribe went
through a LOT of revisions of the firmware on that drive!

I'm always paranoid, so I do use SCSI Parker.  Priam users will
especially like the fact that their drives don't do a panic seek at
powerdown (SMACK!).

C'mon, Apple, put the RIGHT SCSI commands in future Shut Down revisions.
This should be mandatory!

	My views and welcome to them,
		Alex

"Later anthropological experts maintain that the true stake in the heart
of the primitive, so-called USENET computer network was the ``No Amanda
Walker'' clause in the much-debated User's Covenant.  This clause, which
was required to be signed in blood by the users before they could
access, stated that he/she/it/yx would post no messages which could
directly or indirectly be interpreted as having anything to do with work
actually done by that individual in a for-pay job.

"The net result of the clause, says this theory, was that only those who
knew nothing about the subject could comment on it.  Noise levels
spiraled out of sight and use by the self-appointed experts plummeted.

"Yet still others maintain that this was not true, that the entire
problem was caused by the sudden siezure of the only known working
source to the internetworking bridge software by officers of the
so-called Department of Justice..."

		--"Attempts to achieve electronic communications among the
		   ancients", Jones, Klewicky, et al, Journal of Forensic
		   Anthropology
-- 
		Alex Pournelle, freelance thinker
		Also: Workman & Associates, Data recovery for PCs, Macs, others
		...elroy!grian!alex; BIX: alex; voice: (818) 791-7979
		fax: (818) 794-2297    bbs: 791-1013; 8N1 24/12/3