I've been hunting through scsi/*.c and can't find any messages like
the "unknown drive type 7".. I finally realized that this message is
coming from mt! 
  I have a WANGTEK, 6130-HS, 4B18, and NetBSD-sun3 says 

amaterasu# mt -f /dev/rst0 status
7: unknown tape drive type

  drive type 7 is listed in sys/mtio.h as a "SUN" okay...
  And it *is* in the table in mt.c behind a #ifdef sun.
  Further, in the sys/scsi/st.c, at line 1057, it says:

		g->mt_type = 0x7;	/* Ultrix compat *//*? */

  there is no other reference to mt_type, and sure enough, mt.c uses
the MTIOCGET ioctl. 
  It does not appear that the tables get compiled into mt.c at all.
Of course, I can't actually compile mt now because the TMS_BITS,
ARCH_CTRL_BITS, and ARCH_BITS defines aren't (defined).
  I had no problem dumping my root partition to tape.

  Maybe there is stuff still missing from st.c, but things seem to
work now that I've realized that mt status doesn't...