Raid 5Ee Arrays - Adaptec SAS/SATA/SCSI RAID Controllers Installation And User Manual

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
Disk Drives in Logical Drive
Drive Segment Size
250 GB
(Smallest Disk Drive)
250 GB
Disk Drive 1
Disk Drive 2
400 GB
Disk Drive 3
Disk Drive 4
400 GB
Appendix B: Understanding RAID
1 S ... P
2 P ... 449
S 3 ... S
Unused Space = 150 GB
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.
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