Actually, I figured out that the problem I was having with my SCSI disk
was related to queueing and not DMA. Since I set the tagged queue
length to 1 in the BusLogic SCSI driver I haven't had any problems
whatsoever with my SCSI disk, even under fairly heavy load and with the
card's DMA transfer rate turned up to 8 Mbyte/s.
On the other hand, the sound driver works (or fails to work) just as it
did before in DOOM, and after some random amount of time (usually 5-15
minutes of play) the sound stops and I get the "DMA (output) timed out -
IRQ/DRQ conflict?" messsage although no such conflict exists on my
system. I should also note that this happened when I had all IDE disks,
and so far I haven't seen any noticeable difference in this behavior as
a result of using SCSI instead of IDE.