http://www.freebsd.org/doc/ru/books/handbook/disks-adding.html

# dd if=/dev/zero of=/dev/da1 bs=1k count=1
# bsdlabel -Brw da1 auto
# bsdlabel -e da1                           # create the `e' partition
# newfs -d0 /dev/da1e
# mkdir -p /1
# vi /etc/fstab                              # add an entry for /dev/da1e
# mount /1