Adaptec 2268300R manual RAID 5EE Arrays

Appendix B: Understanding RAID ● 100

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 1 250 GB

Disk Drive 2 250 GB

Disk Drive 3 400 GB

Disk Drive 4 400 GB

Disk Drives in Logical Drive

Drive Segment Size

(Smallest Disk Drive)

Disk Drive 1 1 S ... P

Disk Drive 2 2 P ... 449

Disk Drive 3 S 3 ... S

Unused Space = 150 GB

Disk Drive 4 P 4 ... 500

Unused Space = 150 GB

Based on the drive segment sizes used: RAID 5EE Logical Drive = 500 GB plus parity and hot spare.