ISC Problem writing to DOS Partition

[Blake McBride]

There seems to be some sort of IO problem with ISC UNIX when it writes
to a DOS partition.  If you mount a DOS (3.3 30MB DOS) partition and then
write to it - either through UNIX or VPIX - the DOS file system, on
occasion, becomes corrupt.  Yes, I can copy 6 relatively small files
without a problem, and yes, even some large files usually without a problem.
However, I have found that if I am copying a large number of relatively
small files (20K) one-at-a-time, approximately 1 out of 50 doesn't make it.
By "doesn't make it" I mean that the file seems to copy successfully but
after the copy you can check the file with "ls -l" and find that it has
zero bytes.  Then you can unmount the DOS file system, down the system,
reboot under DOS (3.3), and then do a chkdsk.  You will find that the DOS
file system is corrupted and there are missing clusters.

This problem shows itself quite consistently when you try to copy a very
large number of files (~25MB) with a number of sub-directories using
either xcopy in VPIX or tar in UNIX.

This problem is extremely serious!  As a professional software developer
for DOS applications I need to depend on the file system.  Here is a scenario
which has happened to me:  I spend several months developing a DOS application
under UNIX & VPIX.  I do this because of the significantly better development
tools under UNIX and the larger market of DOS.  There are several reasons
why I, at times, must keep my application on a mounted DOS partition
(other ISC bugs & DOS protect mode debugger only works under DOS) which I
won't go into now.  I go to modify a module which has been completed for
several months and find that it has 0 bytes!  Since all of my file copys/saves
appeared successful I had no way of knowing that one of my source files
contents were gone.  And, since the file got clobbered several week ago
all my backups have a 0 length file.  I LOST over a week of work!!!!!!!

I have been in contact with ISC & Multi User Systems about this problem
on and off for over a year.  I am able to duplicate the problem on an
associates machine, so its not my machine.  ISC usually tells me that
they can't duplicate the problem.  On occasion they have said that
A) other people have complained about this problem, and B) they can't
duplicate the problem *reliably*.

This problem is a major problem to me.  I am writing this note for two reasons.
1) to find out if others are experiencing this problem, and 2) to attempt
to get ISC to address the problem.
-- 
Blake McBride				Home (615) 790-8521
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