Create RAID using mdadm
$ mdadm --create --verbose /dev/md0 --level=1 /dev/sda1 /dev/sdb2
Remove failed disk from RAID
$ mdadm --remove /dev/md0 /dev/sda1
Add a disk to an existing array
$ mdadm --add /dev/md0 /dev/sdb1
Verifying the status of the RAID arrays
$ mdadm --detail /dev/md0
Stop RAID arrays
$ mdadm --stop /dev/md0
Start RAID arrays
$ mdadm --start /dev/md0