Folks,
        I have laid my hands on (unfortunately NOT for keepsies) a
Digital TLZ7 tape drive - the unit is a DAT drive with a tape changer
on it.  I have configured the changer device into my kernel and the
drive and changer are recognised during boot, viz:

st0 at scsibus0 targ 5 lun 0: <DEC, TLZ7      (C)DEC, 4BQE> SCSI2 1/sequential removable
st0: st0(ncr0:5:0): 5.0 MB/s (200 ns, offset 8) drive empty
ch0 at scsibus0 targ 5 lun 1: <DEC, TLZ7      (C)DEC, 4BQE> SCSI2 8/changer removable
ch0: 4 slots, 1 drive, 1 picker, 0 portals

But when I try getting the status of the changer I get the following
kernel errors:

ch0(ncr0:5:1): extraneous data discarded.
ch0(ncr0:5:1): COMMAND FAILED (9 0) @0xf875dc00.
ch0(ncr0:5:1): extraneous data discarded.
ch0(ncr0:5:1): COMMAND FAILED (9 0) @0xf875dc00.
ch0(ncr0:5:1): extraneous data discarded.
ch0(ncr0:5:1): COMMAND FAILED (9 0) @0xf875dc00.

and, of course, chio fails with an I/O error.  Any ideas what I can do
with this?  I would like to use the changer if I can....

Also, I don't seem to get as much data onto the tape as I thought I
would - I get around 1Gig onto tape whereas I was expecting more like
4Gig.  Do I need a quirk entry for this sucker?

This is all with an i386 -current as of a few days ago.

FWIW here is the output from prtconf:

System is a i386 architecture on a Intel Pentium (P54C) (586-class)
  with 33157120 bytes of physical memory, 29233152 bytes is non-kernel memory

mainbus0
   pci0
      pchb0 (device = 0, function = 0)
      pcib0 (device = 7, function = 0)
         isa0
            com0 (irq = 4, port = 0x3f8)
            com1 (irq = 3, port = 0x2f8)
            wt0 (irq = 5, port = 0x300, drq = 1)
            sb0 (irq = 7, port = 0x220, drq = 3)
            npx0 (port = 0xf0)
            vt0 (irq = 1, port = 0x60)
            fdc0 (irq = 6, port = 0x3f0, drq = 2)
               fd0 (drive = 0)
               fd1 (drive = 1)
      ncr0 (device = 10, function = 0)
         scsibus0
            sd0 (target = 0, lun = 0)
            sd1 (target = 1, lun = 0)
            st0 (target = 5, lun = 0)
            ch0 (target = 5, lun = 1)

-- 
Brett Lymn, Computer Systems Administrator, AWA Defence Industries
===============================================================================
  "Upgrading your memory gives you MORE RAM!" - ad in MacWAREHOUSE catalogue.