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From: bart@reed.UUCP (Bart Massey)
Newsgroups: net.micro.mac
Subject: Re: Re: Bad Disk Block Horror Story
Message-ID: <2318@reed.UUCP>
Date: Fri, 10-Jan-86 18:23:06 EST
Article-I.D.: reed.2318
Posted: Fri Jan 10 18:23:06 1986
Date-Received: Sun, 12-Jan-86 00:29:05 EST
References: <8601030325.AA25594@kim> <3117@sun.uucp>
Organization: Reed College, Portland, Oregon
Lines: 75

> > I just found out that a disturbingly large number of my floppy disks have
> > bad blocks.
> 
> > But wait again, it is worse yet.  Many times I've had to scavenge and
> > reformat disks when they've been trashed such that "Some files couldn't
> > be read and were skipped", "This disk is unreadable.  Do you want to
> > initialize it?", or "The file copy didn't work.  Try copying to a different
> > disk".  The bad ones were ONLY the latest ones I've found.
> 
> > I don't think I'm the only one with these problems.  Just about everyone I
> > know with a Mac sooner or later finds himself with a file or disk that is
> > corrupted.
>
> Well, at Gordon's suggestion, I went rummaging through my collection. I've got
> somewhere between 150 and 200 disks. In checking about 75 disks (about 10
> blank and initialized ones, all of the ones I use more or less constantly, and
> a random conglomeration of the disks in my archive including a lot of the
> Apple supplied software supplement disks) I found one bad block, which was
> track 33, sector 0 of my Rogue distribution disk -- I bet that is what they
> used for copy protection at that. Everything else came through with no
> problems at all. 
>
> ...
>
> I'd suggest that Gordon's problem is one of a few things:
>     o dirty disk heads -- especially if the problem sectors move around.
>     o misaligned drives
>     o power surges
>     o something magnetic (don't keep your disks on your stereo speaker, be
> 	careful with things like Bart ticket readers, you probably don't want to
> 	keep yours disks on top of your Mac for both heat and magnetic (from the
> 	CRT flyback transformer) reasons.
> 
> I'd guess that he is a special case, not the normal situation (if he was, I
> think we'd have heard a lot of screaming from the users about blown disks, and
> it just doesn't happen). I DO suggest that people check it out, though -- if
> you've got a problem, you want to know so you can get it fixed. If you aren't
> cleaning your disk heads, go out, buy a kit (about $15) and DO IT.
> 
> chuq

     I didn't even  bother to  check all mine  -- I  already
knew I had quite  a number of them  with the problem  Gordon
describes, and the first one I checked had one bad block.  I
tend to agree  with Chuqui's  comments about  what might  be
wrong, although  I  would  also  add  possible  drive  speed
variation problems to the list  -- the speed control  method
used is none too sane.   I suppose I should clean my  drive,
but the fact remains  -- the Mac 3.5"  drives are MUCH  less
resilient than any 5.25"  drive I've ever  worked with.   At
Reed,  we  routinely   have  problems   like  those   Gordon
described, plus quite a problem of incompatibility of  disks
formatted on  one mac  with another  mac!   The most  likely
causes of this are drive speed differences or badly  aligned
drives, but since there is no way to adjust the drive  speed
or realign the drive except to mail it back to Apple (or  so
our service person tells me) it's kind of a moot point -- we
just can't afford to do that in either time or money.

     Three cheers  for  the  rumored  SC(u)SI  port,  if  it
becomes reality -- I'se gunna just git a big hard disk,  and
ignore the  3.5" diskses  forever,  except for  backups  and
interchange with other machines...

     In sum, we at Reed have  heard a LOT of screaming  from
users about blown disks.  Just thought I'd add my two bits.


					Bart Massey
					..tektronix!reed!bart


"Someday, my son, all this will be yours."
"What, the curtains?"
				--Monty Python