Dirty Rotten DMA problem (?) Simultaneous tape & diskette use

[Colonel Panic]

I just encountered some strange i/o errors, and I'm looking for some
collective wisdom...

Platform: AT&T 6386E/33, 24MB of memory, standard AT&T/Wangtek 125 MB
          streaming tape, SV/386 Rel 3.2.2

Situation: while doing a mass cpio to the streaming tape, I try to
           format some 3.5" floppies or dd some disk-resident floppy
           images to them.  I keep getting i/o errors on the diskettes.
           If I try the same operations while the tape drive is not in
           use, no problems arise.

Since both are using DMA, I suspect that the DMA buffering in the
kernel is going haywire.  Current pertinent kernel parms are DMAEXCL=0
(allow simultaneous DMA) and DMAABLEBUF=256.

Does anybody have any other ideas as to possible other causes and/or
possible solutions?

thanks in advance.

--
Alan Denney      aland at informix.com      {pyramid|uunet}!infmx!aland

I'm Pro-Anarchy...   and I Vote!