Yes, I have experienced EXACTLY the same problems as you. It appears that
support for the Archive tape drive and Emulex controller, found in early
Sun3's, is broken and hasn't been fixed, even though I mentioned the
problem more than half a year ago on this list. I worked around the problem
by using Sun's munix, instead of the miniroot, to get NetBSD onto the
machine.

I then began to experience core dumps and other odd failures, and gave up
on using NetBSD on that machine. I still use it on others where it seems to
be more stable.

--Brett