Adaptec SAS/SATA/SCSI RAID Controllers - Manual (Page 74)

Appendix B: Understanding RAID ●
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RAID 5EE Arrays
A RAID 5EE array—also known as a hot space—is similar to a RAID 5 array except that it
includes a distributed spare drive and must be built from a minimum of four disk drives.
Unlike a hot spare, a distributed spare is striped evenly across the disk drives with the stored
data and parity data, and can’t be shared with other logical disk drives. A distributed spare
improves the speed at which the array is rebuilt following a disk drive failure.
A RAID 5EE array 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 figure, S represents the distributed spare, P represents the distributed parity data.
Disk Drive 1
Disk Drive 2
Disk Drive 3
Disk Drive 4
250 GB
250 GB
400 GB
400 GB
Drive Segment Size
(Smallest Disk Drive)
Disk Drive 2
Disk Drive 3
Disk Drive 4
Disk Drive 1
1 S ... P
2 P ... 449
S 3 ... S
P 4 ... 500
Unused Space = 150 GB
Disk Drives in Logical Drive Based on the drive segment sizes used:
RAID 5EE Logical Drive = 500 GB plus parity
and hot spare.
Unused Space = 150 GB