grip / # mdadm --create /dev/md0 -l 5 -n 4 /dev/hda4 /dev/hdb2 /dev/hdc2 missing
mdadm: Cannot open /dev/hda4: No such device or address
mdadm: Cannot open /dev/hdb2: Device or resource busy
mdadm: Cannot open /dev/hdc2: Device or resource busy
mdadm: create aborted