Make a bootable mirror of a disk (don't blame me if this blows up).

This creates one partition (root) and copies everything onto it,
but you can ofcourse change the layout as you wish.  The target
disk is wd1.

It might be a good idea to practice on an empty USB stick first.

# fdisk -iy wd1
# disklabel -E wd1 # add partition(s)
# newfs /dev/wd1a
# mkdir /mnt/new
# mount -o noatime,softdep /dev/wd1a /mnt/new
# cd /mnt/new
# pax -rw -p e <file-list> .
# cp /usr/mdec/boot .
# /usr/mdec/installboot /mnt/new/boot /usr/mdec/biosboot wd1
# mkdir tmp
# chmod 1777 tmp
# vi etc/fstab # if layout has changed
# cd
# umount /mnt/new

<file-list> format is "/bsd /bsd.rd /dev /root" and so on.

Later you can pax with the -u option to only copy modified files.