Path: utzoo!attcan!uunet!zephyr!tektronix!tekgen!tekigm2!phils
From: phils@tekigm2.MEN.TEK.COM (Philip E Staub)
Newsgroups: comp.sys.amiga
Subject: Re: A1000 floppy flakies
Keywords: Bad Blocks, corrupt disks, HELP!!!
Message-ID: <5054@tekigm2.MEN.TEK.COM>
Date: 22 Jun 89 20:24:51 GMT
References: <418@isi.UUCP>
Reply-To: phils@tekigm2.MEN.TEK.COM (Philip E Staub)
Organization: Tektronix, Inc., Vancouver,  WA.
Lines: 43

In article <418@isi.UUCP> mark@isi.UUCP (Mark Bailey) writes:
[ describes drive flakiness ]
>unbelievable number of corrupted files.  Diskdoctor usually ends up finding
>"hard errors" on tracks near 40.  This happens on various media, including
>Fuji and Sony DS/DD.
>
>I just ran the Ami Alignment S/W on the machine and found no problems.

This sounds like the old Delay(0) problem to me. By any chance are you
running an old copy of the Dillon/Drew shell (about version 2.04 or earlier)? 
Or any other old software? If so, get rid of it and see if your problems go
away. 

I haven't personally experienced this in a long time, but the symptoms are
more or less just as you describe: semi-random trashing of disks by making
track 40 unreadable. I don't remember all of the details, so maybe one of
the other old timers can relate the "official" explanation. I was under 
the impression that the problem was fixed in 1.3, but maybe people just 
automatically work around it these days. Basically, the "original" fix was to 
avoid, at *all* costs, calling Delay() with an argument of 0. (The old
"If-it-hurts-to-hit-your-thumb-with-a-hammer-don't-hit-your-thumb-with-a-hammer"
approach.)

Of course, another possible explanation is that with a lot of files on your
disk, you're probably updating directories a lot. They therefore get
re-written more often than most other things, so they are more likely to be
trashed. Since track 40 is the site of the root directory block, all it
takes is for a crash to occur during a directory operation and the root
directory (and the entire track it's written on, thanks to full-track
reads/writes) can be trashed.


>Mark Bailey                                 (I didn't really say this.)
>via:  ...!uunet!pyrdc!isi!mark              ------Have a  8-|  day!!!!!


Hope this helps.
Phil
-- 
------------------------------------------------------------------------------
Phil Staub        
Tektronix, Inc., Vancouver, Washington 98668
phils@tekigm2.MEN.TEK.COM