Adaptec 2268300R User Manual

Appendix B: Understanding RAID

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RAID 6 Arrays

A RAID 6 array—also known as dual drive failure protection—is similar to a RAID 5 array 
because it uses data striping and parity data to provide redundancy. However, RAID 6 arrays 
include two independent sets of parity data instead of one. Both sets of parity data are striped 
separately across all disk drives in the array.

RAID 6 arrays provide extra protection for your data because they can recover from two 
simultaneous disk drive failures. However, the extra parity calculation slows performance 
(compared to RAID 5 arrays).

RAID 6 arrays must be built from at least four disk drives. Maximum stripe size depends on 
the number of disk drives in the array.

RAID 60 Arrays

Similar to a RAID 50 array (see 

), a RAID 60 array—also known as dual drive failure 

protection—is built from eight disk drives configured as two or more RAID 6 arrays, and 
stripes stored data and two sets of parity data across all disk drives in both RAID 6 arrays.

Two sets of parity data provide enhanced data protection, and striping improves performance. 
RAID 60 arrays also provide high data transfer speeds.

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

P1 ...

P2

2

P2 ... 449

P1

3 ...

P1

P2

4 ... 500

Unused Space = 150 GB

Disk Drives in Logical Drive

Based on the drive segment sizes used: 
RAID 6 Logical Drive = 500 GB plus 
parity (P1 & P2)

Unused Space = 150 GB