device.hints isn't setting what I want

[Dan Langille]

Folks,

[please CC me on replies]

First, see also my post: do I want ch0 or pass1?

I have an external tape library and an external tape drive.  They are 
not always powered up.  My goal: always get the same devices regardless 
of whether or not the tape library is powered on at boot.

After booting, with the tape library powered on, I have these devices:

# camcontrol devlist
<QUANTUM DLT7000 1E48>             at scbus0 target 5 lun 0 (sa0,pass0)
<DEC TL800    (C) DEC 0326>        at scbus1 target 0 lun 0 (ch0,pass1)
<DEC TZ89     (C) DEC 1837>        at scbus1 target 5 lun 0 (sa1,pass2)
<HL-DT-ST DVDRAM GSA-H10A JL02>    at scbus2 target 0 lun 0 (cd0,pass3)
<USB 2.0 Storage Device 0100>      at scbus5 target 0 lun 0 (da0,pass4)

In /boot/devices, I have added these entries:

hint.scbus.1.at="ahc0"
hint.scbus.0.at="ahc1"
hint.scbus.2.at="acd0"
hint.scbus.5.at="umass0"

The first two lines ensure I always get the QUANTUM drive at sa0, and 
the DEC at sa1.  That part works.

The second two lines aren't doing as expected.

If the external tape library is not powered up, I get:

# camcontrol devlist
<QUANTUM DLT7000 1E48>             at scbus0 target 5 lun 0 (sa0,pass0)
<HL-DT-ST DVDRAM GSA-H10A JL02>    at scbus3 target 0 lun 0 (cd0,pass1)
<USB 2.0 Storage Device 0100>      at scbus7 target 0 lun 0 (da0,pass2)

Then, after powering up, and doing a rescan all, I get:

  # camcontrol devlist
<QUANTUM DLT7000 1E48>             at scbus0 target 5 lun 0 (sa0,pass0)
<DEC TL800    (C) DEC 0326>        at scbus1 target 0 lun 0 (pass3,ch0)
<DEC TZ89     (C) DEC 1837>        at scbus1 target 5 lun 0 (pass4,sa1)
<HL-DT-ST DVDRAM GSA-H10A JL02>    at scbus3 target 0 lun 0 (cd0,pass1)
<USB 2.0 Storage Device 0100>      at scbus7 target 0 lun 0 (da0,pass2)

So... I could keep the unit powered on all the time, but that's really 
not what I want to do.

Clues please?

Full dmesg output at http://www.langille.org/tmp/dmesg.boot