mdadm: option must be given to set the mode

mdadm: An option must be given to set the mode before a second device

A hard drive was thrown out of my raid 5 array and had to be readded.

The command gave the following error as you see above.

Solution to get it working:

root@homeserver:/home/mathias# mdadm /dev/md0 -a /dev/sdb1
mdadm: re-added /dev/sdb1


And now the raid array is syncing again :)

root@homeserver:/home/mathias# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1] [raid10]
md0 : active raid5 sdb1[4] sdc1[3] sdd1[1]
 5860259840 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [_UU]
 [>....................] recovery = 0.8% (24866428/2930129920) finish=262.8min speed=184190K/sec
 bitmap: 11/22 pages [44KB], 65536KB chunk

unused devices: <none>