SCO Xenix 286 2.2.1 panics during backup

[Paul De Bra]

In article <229 at libove.UUCP> root at libove.UUCP (Jay M. Libove) writes:
>In article <226 at libove.UUCP>, I wrote:
>> Oh dear, do _I_ have a problem!  I have a PCs Limited AT running at
>> 6 MHz, with SCO Xenix for the 80286, version 2.2.1.
>> 
>> I have tried using afio and pax to backup the system to the high
>> density (1.2 megabyte) floppy drive, and both times the system panicked
>> with a stack fauly some time before the end of the second disk was
>> written out (not to a particular file or track/sector combination I
>> don't think)...
>> 
> [ comments about how I could but don't wish to use 'backup' ]
>> 
>> Does someone have any suggestions, or have experienced the same
>> trouble with system panics? The only time the system has panicked in
>> the past six months is during backups!
>> 
>

I have experienced exactly the same problem shortly after I bought a no-name
clone about 2 years ago. The system (running 2.1.3 at that time, but later
changed to 2.2.1 with no improvement to the situation) would NEVER panic,
except when I tried to access the floppy drive. The more activity on the
system the more likely a panic. The only way I could make backup was to go
into single user mode, and then it would work about 2 times out of 3.
A friend of mine bought the same system at the same time, but as we discovered
later, he got a different floppy/hard disk controller.

After about a year I installed a second hard disk, and a new disk controller
to replace the old one. (the old one was bad) The panics went away instantly.
The system NEVER had a panic during backups anymore.

So maybe your problem is the same: a disk-controller that is not completely
100% reliably equivalent to the WD controller it tries to emulate. The bad
controller I had was something using a 4Mhz Z80 with a program in eprom,
and no custom vlsi chips or anything.

The WD controller I got afterwards and the DTC controller my friend has
never caused any problem.

Paul.
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