well im using this guide  -  https://www.digitalocean.com/community/tutorials/how-to-create-raid-arrays-with-mdadm-on-ubuntu-18-04

 and i got to the part where you need to type : "
 mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/disk1 /dev/disk2

and it prompts back :

mdadm: super1.x cannot open /dev/nvme0n1: Device or resource busy
mdadm: ddf: Cannot use :/dev/nvme0n1: Device for resource busy
mdadm : Cannot use /dev/nvme0n1 : It us busy
mdadm : Cannot open /dev/nvme0n1: Device or resource busy