Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!wuarchive!uunet!jarthur!nntp-server.caltech.edu!toddpw
From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: GS/OS Error code $51
Message-ID: <1991Feb22.180320.1483@nntp-server.caltech.edu>
Date: 22 Feb 91 18:03:20 GMT
References: <1991Feb21.164213.16068@HQ.Ileaf.COM>
Distribution: usa
Organization: California Institute of Technology, Pasadena
Lines: 37

trm@HQ.Ileaf.COM (Tom Madigan x3438) writes:

>I'm currently unable to add or delete files from either partition 
>on my hard disk. The error code I'm getting is "Error code 51" which 
>(I think)translates into a screwed up directory table(number of entries 
>!= number of files).

What a coincidence ... I just got done de-fluffing my hard drive of that
type off error... by any chance did you do some large directory (as in LOTS
of files) copies recently?

>Is there a utility out there that can help me salvage this?

Well, the only commercial thing I know of is Bag of Tricks, but it's pretty
archaic and doesn't support any of the GS specific changes to prodos. In fact,
it's damn annoying because it stops you on every file that has lower case
characters in the filename (which is legal because those bits were reserved
when BOT was written).

over the last few days I've written a prodos file system integrity checker
and repair help package, in Orca/C and designed to use the I/O redirection
of the shell. The integrity checker is automatic, but the rest of the
utilities are very hands on and you'll need to be familiar with prodos disk
structures to use them properly. The repairs I did last night (all last night)
were conceptually simple but nontrivial from a software perspective -- it is
NOT easy to write a utility that will automatically figure out what's happened
when the only symptom is that the index block was never written to disk. I'm
convinced that there is a really subtle bug in the prodos FST and how it
handles write-deferred filesystem blocks. I am using 5.0.4 and have been since
before the last time the problem manifested itself (a backup/reformat done to
salvage data damaged by exactly the same anomaly!!).

If anyone is interested, mail me -- if there are enough requests I will put
a more complete description on the net.

Todd Whitesel
toddpw @ tybalt.caltech.edu


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