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Date: Tue, 02 Jun 2009 19:04:07 -0400
From: Bill Cole <listbill@scconsult.com>
Organization: Solid Clues
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Subject: Re: Final task
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lcs@spellnetwork.com wrote, On 6/2/09 3:44 PM:
> You are correct - there is a disk issue - but only with 1 account - all
> other accounts are fine and I can copy them. When I try to copy my
> account to another box, I get error -50 can't be copied. There is
> probably come corruption but it's hard to find repair utilities for MAC
> OS 9 still around.
>
> Thanks for the help. If I can find some utility to repair the file and
> let me copy it - i will use the command you sent.


Apple's Disk First Aid will very rarely fail where other MacOS 9 utilities 
can do anything useful in recovering a corrupted disk. You can still 
download DFA from http://support.apple.com/kb/TA26794?viewlocale=en_US if 
you don't have it already.

Among the third party utilities, Alsoft DiskWarrior can sometimes recover a 
corrupted disk where DFA gets lost. I would not bet on it in this case, but 
if you can find a copy that will run on OS9, it would be worth trying if DFA 
fails on a logical problem. If you can dig up a very old Norton Utilities, 
it had a very low level scanning function that can reconstruct some files, 
but it is extremely slow and frequently yields more junk than usable files.

If you can get the disk connected to a OSX machine, Apple's Disk Utility is 
still the best first thing to try, although again DiskWarrior would be the 
second line tool. Ultimately, the 'dd' utility (a classic Unix tool) can be 
helpful in extremis if you absolutely positively must get everything 
recoverable from a dead disk that will not mount and can't be fixed due to 
hard errors. The process for that is slow and profoundly geeky: you can use 
dd to do a block-by-block copy of the disk (null-filling unreadables as you 
go rather than failing or skipping them) onto a non-failing disk, then using 
Disk Utility on the result to clean up the filesystem on the new disk. If 
you get that desperate, let me know and I'll go digging for the exact 
commands I used to recover a disk that way a few years ago...

A -50 error is often a sign of total hopelessness, particularly when seen 
mixed with -36 errors. Typically an app will get a -36, and the Finder will 
take a longer time to give you a -50. The reason for that is that the Finder 
has fallback approaches below the filesystem that it tries after getting a 
-36 from the normal file open call, and the lower level calls yield a -50. 
Occasionally you can get that from flaky SCSI or unusual forms of filesystem 
corruption that include file cross-links, but most often it means that the 
disk used up its supply of spare sectors (that are used for invisibly 
remapping borderline sectors) at some point far enough in the past that 
you've managed to get a solidly unreadable block allocated to a file that 
you want to read. This is very much a case of walking on very thin ice with 
that disk: it may or may not have a very large number of sectors that are 
marginal or bad, but statistically you are very unlikely to just happen to 
find the only one.

Bottom line: This error pattern is an evacuation notice. Do not trust that disk.