MDADM – Meta Device Admin. Apparently.

Sometimes, you wanna trash your RAID. But Linux starts it up while you’re not looking, and locks your block devices.

In a terminal, lets break it.
sudo -i
Here we become root, not user.

cat /proc/mdstat
Here, we can see our RAID devices that are started. eg, md126 md127 etc.

mdadm –manage –stop /dev/md127
Here, we manage the device, and use the stop flag, telling MDADM to stop the raid device. With this done, now we can work on the underlying disks. You’ll need to do this for each raid device.

Have fun.