mdadm --create /dev/md2 --level=0 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
mdadm: /dev/sda1 appears to contain an ext2fs file system
size=245111704K mtime=Sat Aug 19 23:54:43 2006
mdadm: /dev/sdb1 appears to contain an ext2fs file system
size=244196000K mtime=Sat Aug 19 23:54:43 2006
mdadm: /dev/sdc1 appears to contain an ext2fs file system
size=312568640K mtime=Sat Aug 19 23:54:43 2006
mdadm: /dev/sdd1 appears to contain an ext2fs file system
size=245111704K mtime=Sat Aug 19 23:54:43 2006
Continue creating array? Y
mdadm: SET_ARRAY_INFO failed for /dev/md2: Invalid argument