so i started to create a RAID5 array on my homemade server with 4x 1.5tb drives (about 1.3TB) around 2PM yesterday. checked on the array today at 10:15am and found it was done- or so i thought.
root@Furnace:/home/poochief# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdd1(S) sde1 sdc1 sdf1(F)
4395403776 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/2] [_UU_]
unused devices: <none>
according to a nice fellow on the #debian channel, "_UU_" would indicate 2 drives down, 2 up and accordingly sdd1(S) being a 'spare' while sdf1(F) being a failed drive. the nice fellow had to leave early so i'm not entirely sure what to do.
mdadm version: 3.1.4 31st august 2010.