fdisk /dev/da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=121601 heads=255 sectors/track=63 (16065 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=121601 heads=255 sectors/track=63 (16065 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 63, size 1953520002 (953867 Meg), flag 80 (active)
    beg: cyl 0/ head 1/ sector 1;
    end: cyl 768/ head 254/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>

fdisk -BI [drive]
bsdlabel -wB [drive]s1
newfs [drive]s1a

mount [drive]s1a /mnt

# newfs /dev/da0s1
# mount -t ufs /dev/da0s1 /mnt/usbdisk
# ls -ltr /mnt/usbdisk
total 2
drwxrwxr-x  2 root  operator  512 Nov  6 18:11 .snap