DMA (maybe) and tape drive problem (PANIC)

[Craig W. Shaver]

In article <1990Aug20.052225.3371 at jersey>, zaz at jersey (Todd Koeckeritz) writes:
> I have run into a rather hard to solve problem and would appreciate
> any input all you netters might have.  I have a 386 (Mylex MX Revision
> 1.01 25Mhz) motherboard, an Archive VP402 card controlling an Archive
> 150M VP tape drive and an Adaptec ACB-2322B controlling a 300M disk
> all running under Xenix SysV 2.3.2.  The problem I am having is that I

I have locked up an interactive unix system using my archive tape.
I have had problems using tar on this tape under esix when the
buffer count was not 10 or 100.  Cannot remember crashing the system
on esix though (rev. C).  

	mylex 386/20
	adaptec 1542b + micropolis 1684-7 + archive s150

I am not ready to blame mylex, but I think the dma could be a problem.
I believe the scsi has its own dma, and the crash can be consistently caused
by using the tape dev that is not supposed to wait for rewind.  BUT -- this
only crashed on ix, not on esix.

I have had trouble with a 60mb tape using the everex controller which should
be similar to your archive controller.  The tapes were not written properly
and tapes from another machine did not produce correct files when read.

My conclusions are that for the scsi the drivers are to blame, but for the
60mb using the qic02/24 adapter it could be the bus speed and dma problems.

	Craig W. Shaver


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