Appendix B: Selecting the Best RAID Level ● 158RAID 5EE Logical DrivesA RAID 5EE logical drive—also referred to as a hot space—is similar to a RAID 5 logical driveexcept that it includes a distributed spare drive and must be built from a minimum of four diskdrives.Unlike a hot spare (see page 54), a distributed spare is striped evenly across the disk drives withthe stored data and parity data, and can’t be shared with other logical disk drives. A distributedspare improves the speed at which the logical drive is rebuilt following a disk drive failure.A RAID 5EE logical drive protects your data and increases read and write speeds. However,capacity is reduced by two disk drives’ worth of space, which is for parity data and spare data.In this example, S represents the distributed spare, P represents the distributed parity data.Disk Drive 1Disk Drive 2Disk Drive 3Disk Drive 4250 GB250 GB400 GB400 GBDrive Segment Size (Smallest Disk Drive)Disk Drive 2Disk Drive 3Disk Drive 4Disk Drive 11 S ... P2 P ... 449S 3 ... SP 4 ... 500Unused Space = 150 GBDisk Drives in Logical DriveUnused Space = 150 GB= 500 GB plus Parity and SpareRAID 5EELogical Drive
