Simon Burge writes:
>I think you missed the point here - by explicitly specifying
>
>	sd0 at scsibus0 target 0 lun 0
>
>in your kernel config file, you do wire down sd0 at scsibus0, ID 0 and
>lun 0.  Any disks that aren't wired down are caught by an entry like
>
>	sd*     at scsibus? target ? lun ?      # SCSI disk drives
>
>and with the catch-all entry, device renaming will occur.  It's not
>exactly the same as the SYSV mechanism, but you can wire down disks
>if you want to.  This may even be the recommended practice - I can't
>remember, but I always wire down disks.

No, I knew about that already.

My system has three wide SCSI buses, and I could say:

ahc0 at pci0 dev 13 function 0
ahc1 at pci0 dev 14 function 0
ncr0 at pci0 dev 15 function 0

scsibus0 at ahc0
scsibus1 at ahc1
scsibus2 at ncr0

sd0  at scsibus0 target 0  lun 0
sd1  at scsibus0 target 1  lun 0
sd2  at scsibus0 target 2  lun 0
sd3  at scsibus0 target 3  lun 0
sd4  at scsibus0 target 4  lun 0
sd5  at scsibus0 target 5  lun 0
sd6  at scsibus0 target 6  lun 0
sd7  at scsibus0 target 7  lun 0
sd8  at scsibus0 target 8  lun 0
sd9  at scsibus0 target 9  lun 0
sd10 at scsibus0 target 10 lun 0
sd11 at scsibus0 target 11 lun 0
sd12 at scsibus0 target 12 lun 0
sd13 at scsibus0 target 13 lun 0
sd14 at scsibus0 target 14 lun 0
sd15 at scsibus0 target 15 lun 0
sd16 at scsibus1 target 0  lun 0
sd17 at scsibus1 target 1  lun 0
sd18 at scsibus1 target 2  lun 0
sd19 at scsibus1 target 3  lun 0
sd20 at scsibus1 target 4  lun 0
sd21 at scsibus1 target 5  lun 0
sd22 at scsibus1 target 6  lun 0
sd23 at scsibus1 target 7  lun 0
sd24 at scsibus1 target 8  lun 0
sd25 at scsibus1 target 9  lun 0
sd26 at scsibus1 target 10 lun 0
sd27 at scsibus1 target 11 lun 0
sd28 at scsibus1 target 12 lun 0
sd29 at scsibus1 target 13 lun 0
sd30 at scsibus1 target 14 lun 0
sd31 at scsibus1 target 15 lun 0
sd32 at scsibus2 target 0  lun 0
sd33 at scsibus2 target 1  lun 0
sd34 at scsibus2 target 2  lun 0
sd35 at scsibus2 target 3  lun 0
sd36 at scsibus2 target 4  lun 0
sd37 at scsibus2 target 5  lun 0
sd38 at scsibus2 target 6  lun 0
sd39 at scsibus2 target 7  lun 0
sd40 at scsibus2 target 8  lun 0
sd41 at scsibus2 target 9  lun 0
sd42 at scsibus2 target 10 lun 0
sd43 at scsibus2 target 11 lun 0
sd44 at scsibus2 target 12 lun 0
sd45 at scsibus2 target 13 lun 0
sd46 at scsibus2 target 14 lun 0
sd47 at scsibus2 target 15 lun 0

This would capture mostly what I want.

Have you ever tried "MAKEDEV sd47"?  Compare the device files
made with those of sd15.  It does not do the right thing.

Your response also missed every other point made in my email.

Even if "MAKEDEV sd47" worked, it is easier to refer to that 
device as c2t15d0 than sd47, because the name makes more sense.

Can I put:  "c2t15d0 at scsibus2 target 15 lun 0" in the config file?
Could I then use /dev/c2t15d0 as a tape device?  If the system was
booted with c2t15d0 turned off, and then I turned it on, could I
then start dumping a filesystem to a tape there?

Are there any mainstream UNIX (or UNIX-like) OSes which dynamically
name SCSI devices on boot-up?

-- Chuck