mdadm --manage /dev/md125 -a /dev/sdb4 mdadm: add new device failed for /dev/sdb4 as 3: Invalid argument Dec 19 01:23:48 storageboxtest kernel: [ 2328.854491] md: sdb4 does not have a valid v1.2 superblock, not importing! Dec 19 01:23:48 storageboxtest kernel: [ 2328.854499] md: md_import_device returned -22 #zero the superblock and try again! mdadm --zero-superblock /dev/sdb4 mdadm --ma........

mdadm --manage /dev/md1 --add /dev/sdb1 mdadm: metadata format 00.90 unknown, ignored. mdadm: metadata format 00.90 unknown, ignored. mdadm: metadata format 00.90 unknown, ignored. mdadm: /dev/sdb1 not large enough to join array md1's first primary member /dev/sda3 has 57394 cylinders while the /dev/sdb1 has 57393 (1 less cylinder) which is why it won't work. fdisk -l /dev/sda3 Disk /dev/sda3: 47........