Path: utzoo!utgpu!attcan!uunet!husc6!bloom-beacon!mit-eddie!rutgers!att!mtuxo!mtgzz!drutx!druhi!dlm
From: dlm@druhi.ATT.COM (Dan Moore)
Newsgroups: comp.sys.atari.st
Subject: Re: ***HELP*** Floppy gone crazy!?!?!
Message-ID: <3307@druhi.ATT.COM>
Date: 3 Aug 88 15:37:40 GMT
References: <880801064254.135611@HIS-PHOENIX-MULTICS.ARPA>
Organization: AT&T, Denver, CO
Lines: 54

in article <880801064254.135611@HIS-PHOENIX-MULTICS.ARPA>, Friesen@HIS-PHOENIX-MULTICS.ARPA says:
> I just decided that the floppy I use to store my word processor files
> and some other misc.  things, probably had a lot of files I could get
> rid of.  I decided to take a look at them and see which ones to throw
> out.  I had never noticed anything strange about this disk before (the
> only time I access the disk is from file selector boxes, and I always
> know exactly what I want) so I really hadn't "looked" at the disk.
> Well, I got the directory up and much to my surprise, there were many
> groups of two files with exactly the same name.  I opened the files
>...
> 
> Aric Friesen
> 
> Addresses:  Genie:  A.FRIESEN ARPA:  Friesen%PCO@BCO-MULTICS.ARPA

	You have just found one of the more bothersome bugs in GEMDOS. 
When GEMDOS opens a file for write it sometimes fails to delete the
current file first.  This means you can end up with 2 (or 50 for that
matter) files with the exact same name.  Most people won't notice that
this has happened since the standard desktop code won't display
duplicates (the sort routine used in DESKTOP.APP deletes duplicated
entries).  Some shells will show duplicated files, some won't.

	FIXES:  Find a shell (eg. Micro C-Shell from BDT) that will
rename a single file, not all files with the same name.  Rename each
duplicate to a scratch name (eg. dup1, dup2, etc.).  Then look at each
copy and decide whether or not to keep it.  Delete all the unwanted ones
and rename the one you kept back to the original name.

	PREVENTION: there is *no* 100% sure way of preventing this from
happening.  It is distantly related to the "40 folder limit" (common
data structures are used for folders and files; sometimes GEMDOS will
create several entries for a single file or folder which can lead to
duplicated files).  I would really suggest using GEMBOOT, it checks the
number of folders online and creates enough entries for them in the
table.  The next best solution is FOLDERXXX.PRG which allows you to add
any number of additional entries to the table.  Finally, reboot on a
semi-regular basis.  That lets you start over with a "virgin" machine,
which is more likely to work correctly.

	I'd also suggest looking at your disks at least once a day (if
you use the machine a lot) to check for duplicated files.  It's also a
good idea to run a disk test program on a regular basis.  Dave Small and
I wrote one called CHK that was published in ST-Log a couple of months
ago.  There are others that seem to work pretty well also.  These
programs will check for errors in the file system on the disk and then
give you a status report based on what they find.  Very similar to what
CHKDSK does for MSDOS.

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	Dan Moore				ex-Data Pacific programmer,
	AT&T Denver				technical support, hardware
	dlm@druhi.ATT.COM			tester and general go-fer.
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