ha-db1# gmirror label -v -b round-robin gm0 /dev/ad4s1
gmirror: Can't store metadata on /dev/ad4s1: Operation not permitted.
ha-db1# sysctl kern.geom.debugflags=16
kern.geom.debugflags: 0 -> 16
ha-db1# gmirror label -v -b round-robin gm0 /dev/ad4s1
gmirror: Can't store metadata on /dev/ad4s1: Operation not permitted.
 
ha-db1# disklabel /dev/ad4s1
# /dev/ad4s1:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:  1048576        0    4.2BSD     2048 16384     8
  b: 25165824  1048576      swap
  c: 72340632        0    unused        0     0         # "raw" part, don't edit
  d: 25165824 26214400    4.2BSD     2048 16384 28528
  e: 20960408 51380224    4.2BSD     2048 16384 28528