Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ucbvax!ucdavis!uop!exodus
From: exodus@uop.edu (G.Onufer)
Newsgroups: comp.sys.atari.st
Subject: Beware: Munged HD ahead
Message-ID: <966@uop.edu>
Date: 25 Jan 88 15:48:07 GMT
Organization: UoP-- Sun Lab Administration
Lines: 51


Just in case this should happen to any fellow HD owners...

Configuration:
	-Atari SH204, replaced the Tandem drive with a Micropolis 1304 (a la SUN
	 Corp).
	-Runs with the Supra Autoboot program, foldrxxx.prg, Beckemeyer's Hd
	 accelerator.
	-Formatted with the Supra Software (and possibly this time with the ICD
	 software... I cannot remember)
Problem:
	I ran Supra's partition check software in the 'destroy' mode on Partition
	'D' (~13 Megs).  Partition 'E' was trashed afterwards.
Diagnosis:
	Partition 'D' possibly had an 'orphan' sector at the end which was not part
	of a clustor.  Might be caused by either Supra's or ICD's partitioning
	software.  Supra's Partition check program assumed it _was_ part of a
	cluster and tested the _next_ sector also... Partition E's logical boot
	sector.  That sector was found to have the Test pattern in it (the ASCII
	set over and over).
Cure:
	Made my own logical boot sector for Drive 'E' ... creating and testing
	the it as I went.  (Re-boot each time you change a boot sector -- 
	only way to get the computer to recognize the new values).  DLII and
	Disk Doctor are essential.  DLII for its checking capabilities.  Disk
	Doctor because it will let you edit a partition with a mangled boot 
	sector-- DLII will _not_.
Planning ahead:
	Besides the usual backups, keep around a dump of the boot sectors of
	all of your partitions as well as the physical boot sector of the drive.
	Otherwise you will have to re-format your drive after recovering as much
	data as possible from the one messed up partition.  It's a good idea
	anyways.  Perform an image backup (i.e. Tom Hudson's Backup Program
	from STart) every once in a while if your are in the Turtle Camp.
	The image backup can save your life and takes little time (just more
	disks).
****
Now, if anybody has any other clues to why this happened to me (or why
I am wrong), Please let me know.  I spent 5 hours re-constructing the 
mangled partition to get the recent, un-backed-up, work that was on it.
It wasn't fun.  Possibly some disk/directory editors that had a mode for
fixing disks... DLII bombs if something in the BPB (BIOS Parameter Block)
is even slightly wrong.  Disk Doctor did some strange things (filled my 
monochrome screen with static, or something pretty close).  [That was a 
hint, btw.  I don't have the time, but someone may have!].
DO NOT LET THIS HAPPEN TO YOU.  DO NOT BELIEVE A PROGRAM'S "NON-DESTRUCTIVE"
MODE or that it will restrict its actions to a particular area of memory
or disk.

G. Onufer
exodus@uop.edu