root@ubuntu:~# lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT
NAME     SIZE FSTYPE            TYPE MOUNTPOINT
sda      3.7T                   disk
└─sda1   3.7T linux_raid_member part
sdb      3.7T                   disk
└─sdb1   3.7T linux_raid_member part
sdc      3.7T linux_raid_member disk
sdd      3.7T                   disk
sde      1.8T                   disk
└─sde1   1.8T ext4              part /media/2terra
sdf      5.5T                   disk
└─sdf1   5.5T ext4              part /media/movies
sdg      3.7T                   disk
sdh      3.7T                   disk
sdi    232.9G                   disk
├─sdi1 224.9G ext4              part /
├─sdi2     1K                   part
└─sdi5     8G swap              part [SWAP]
sr0     1024M                   rom
root@ubuntu:~# mdadm --zero-superblock /dev/sda
mdadm: Couldn't open /dev/sda for write - not zeroing
root@ubuntu:~# mdadm --zero-superblock /dev/sdb
mdadm: Unrecognised md component device - /dev/sdb
root@ubuntu:~# mdadm --zero-superblock /dev/sdc
mdadm: Unrecognised md component device - /dev/sdc
root@ubuntu:~# mdadm --zero-superblock /dev/sda1
mdadm: Couldn't open /dev/sda1 for write - not zeroing
root@ubuntu:~#