# mdconfig -s 100m
md0
# gpart create -s gpt md0
md0 created
# gpart show md0
=> 40 204720 md0 GPT (100M)
40 204720 - free - (100M)
# gpart add -t freebsd-boot -s 128k md0
md0p1 added
# gpart add -t freebsd-ufs md0
md0p2 added
# gpart show md0
=> 40 204720 md0 GPT (100M)
40 256 1 freebsd-boot (128K)
296 204464 2 freebsd-ufs (100M)
# gpart
# dd if=/dev/zero of=/dev/md0 count=10
10+0 records in
10+0 records out
5120 bytes transferred in 0.003832 secs (1336214 bytes/sec)
GEOM: md0: the primary GPT table is corrupt or invalid.
GEOM: md0: using the secondary instead -- recovery strongly advised.
# gpart show md0
=> 40 204720 md0 GPT (100M) [CORRUPT]
40 256 1 freebsd-boot (128K)
296 204464 2 freebsd-ufs (100M)
# gpart destroy -F md0
md0 destroyed
# gpart show md0
gpart: No such geom: md0.