Disk 5 (new) added to the array (so there should be nothing on it). Disk 3 failed 2 days ago and I shut it down until i just got the 12tb replacement today and when i boot the system up, tried to replace disk 3 but wont let me (due to many changes) that's why i posted here coz, i don't know what to do.
So when the rebuild is done. Disk 5 (should show as "green")? then i can replace disk3 with the WD 12tb? then after that, remove the disk from the enclosure then rebuild disk 5 (again?)