I added a DIOCWDINFO to /sys/arch/sparc/scsi/sd.c to let me use
disklabel to make a c partition in the memory copy of the
label (no -r to disklabel(8)). (Thanks Charles)

This was enough to let me dd the disk image across, reboot, and get a
proper label on disk.

The question still remains, though - what if I hadn't had identical
disks?

--
Dan.

------------------------------------------------------------------------------