Run offline diagnostic on this drive, it may be faulty. Otherwise, replace the drive with another of similar specifications and capacity.
I have an old PowerEdge 2900. I'm not the only person with access to the server. I have current backups for the data. One of this server's RAID arrays has (should have) six disks in a RAID-5 array. These disks are 136 GB, 15k rpm Fujitsu disks. My newly upgraded OpenManage Server Administrator says that this array is degraded, and shows only five of the six disks as part of the array. (System, Storage, PERC 6/i Integrated, Virtual disks, "SAS Array".) The sixth disk shows "Ready". (System, Storage, PERC 6/i Integrated, Connector 1 (RAID), Enclosure (Backplane), Physical Disks) This disk is a Dell-branded disk; it has slightly less space than the Fujitsu disks (136.12 GB vs 136.38 GB). The alert log shows that this sixth disk was unassigned as a global hot spare (?!) and was cleared.  What I can't do: Replace a member disk in "SAS Array", because it says "no disks are available". What I'd like to do: Remove the sixth disk, and replace it with a Fujitsu disk. I have spare Fujitsu disks on-hand.  There are no drop-down options to remove the sixth disk. It looks to me like I just have to bite the bullet and pull that disk as it is now. Then replace it with the Fujitsu disk. I imagine that I'd then configure it as a global hot spare, and the controller would automatically add it to "SAS Array". Am I right about that, or am I about to get my tail caught in a crack?
PERC 6/i says SAS array (6 disks in RAID-5) degraded. One of the six disks is 
"Ready". I want to replace it.