Viewing partitions in FreeBSD

Reformat both disks as UFS

Shell to the device.

freenas:/# gpt show /dev/ad0
       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34  5860533101      1  GPT part - FreeBSD UFS/UFS2
  5860533135          32         Sec GPT table
  5860533167           1         Sec GPT header

freenas:/# gpt show /dev/ad1
       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34  5860533101      1  GPT part - FreeBSD UFS/UFS2
  5860533135          32         Sec GPT table
  5860533167           1         Sec GPT header

For RAID: format the disks individually as software RAID:

freenas:/# gpt show /dev/ad0
       start        size  index  contents
           0  5860533168

freenas:/# gpt show /dev/ad1
       start        size  index  contents
           0  5860533168

after creating the RAID and formatting it as UFS

freenas:/# gpt show /dev/mirror/RAID1p1
       start        size  index  contents
           0  5860533100