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From: rnelson@eecs.wsu.edu (Roger Nelson - Grad Student)
Newsgroups: comp.sys.amiga.tech
Subject: HD validation error (possible cause?)
Message-ID: <1991Jan13.213610.16726@eecs.wsu.edu>
Date: 13 Jan 91 21:36:10 GMT
Reply-To: rnelson@yoda.UUCP (Roger Nelson - Grad Student)
Organization: Washington State University, Pullman
Lines: 44

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Considering the number of people that have been complaining about the
header corruption/validation error, it would appear that there is a real
problem with the File System.

I usually get the error when ever two applications access the HD at the 
same time.  For example, I always get this error whenever I unarchive two 
files simultaneously with lharc to the HD. 

I now do everything in ram and copy to the HD; this is unacceptable.
I got the Amiga for its multitasking abilities which I need for my
research.  My research project requires several processes writting to
the hard drive.

Has anyone else noticed a pattern of validation errors other than those
cause by programs terminating or crashing without closing files?

Did the old file system have this problem, and is it fixed in 2.0?

Without anything else to go by, I would venture to guess that under
certain circumstances two different files are allocated that same block;
as if the task that allocates the file block switchs out before it can
finish marking the block as allocated.
I would be especially suspicious if blocks are allocated sequentially.
That is, if two tasks are writing to two files simultaneously, would the
allocated blocks be interleaved something like:

-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--
file1|file1|file2|file1|file1|file2|file1|file2|file1|file2|file2|file2|
-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--

If this is the case, wouldn't it make more sense to start block allocation
in a sector where there currently isn't any disk activity when the file is
opened?  This would probably also help alleviate fragmentation.

_____________________________________________________________________
      ______________
____  | ^          |    Roger Nelson          rnelson@yoda.eecs.wsu.edu
\^^ |*| ^          |    Agricultural Engineering Department     ///
 |^^//  ^^         |    Computer Science Department            ///
 |  '  ^          +|    Washington State University        \\\///
 \_  ^    _________|    Pullman, WA 99164                   \XX/
   `-----'