1. I would never use Green or Red drives in a server.  I would suggest getting Dell-certified enterprise drives as a first step in troubleshooting. 2. You will only use 500GB of the 1TB available and the rest of the space will not be usable.  You will have to reconfigure the RAID 5 from scratch to go from a 4-disk RAID 5 to a 3-disk RAID 5. 3. Remove the drive, replace the drive, and rebuild it into the array.  As stated though, you can't go from 4 disks in a RAID 5 to 3. Suggestion 1:  Get certified or enterprise drives.  Don't use desktop/NAS drives. Suggestion 2:  Don't use RAID 5 unless you have to.  RAID 10 would be faster in most cases. Note:  The S100 is a very low-end software RAID controller - you should not expect good performance from it.
Hello, I have Dell T110 with S100, configured as below: Raid 5 (disk 0:0, 0:1, 0:2) + Hot Spare (0:3). the first tow disks are (Dell original 500 G.B 7.2k), and the rest are WD 500 G.B 64MB, Green!. actually, after i add these tow WD disks, later i found that the rpm of this disks not 7.2k, it's intellipower as WD mention on their website. In the performance, it's a little bit slow i can see. Q1: is it no problem to keep this setup as it's? or i should again replace the WD with 7.2k to match the exist Dell Disks. Q2: if i change the last disk in Raid 5 with (1T.B) 7.2k will solve the weakness? i don't know what will happened with raid 5 with (500 G.B x2 + 1T.B) Q3: how i can replace that disk without losing any data?  thanks for reading.
Help with T110 S100 Controller