RAID 6 ArraysA RAID 6 array—also known as dual drive failure protection—is similar to a RAID 5 array because it usesdata striping and parity data to provide redundancy. However, RAID 6 arrays include two independentsets of parity data instead of one. Both sets of parity data are striped separately across all disk drivesin the array.RAID 6 arrays provide extra protection for your data because they can recover from two simultaneousdisk 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 numberof disk drives in the array.Unused Space = 150 GBDisk 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 1Unused Space = 150 GBDisk Drives in Logical Drive Based on the drive segment sizes used:(P1 & P2)RAID 6 Logical Drive = 500 GB plus parityP21 P1 . . .4492 P2 . . .P1P1 3 . . .500P2 4 . . .RAID 60 ArraysSimilar to a RAID 50 array (see RAID 50 Arrays on page 68), a RAID 60 array—also known as dual drivefailure protection—is built from eight disk drives configured as two or more RAID 6 arrays, and stripesstored 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 60arrays also provide high data transfer speeds.69Proprietary and Confidential to PMC-Sierra, Inc.Document No.: CDP-00277-01-A Rev. A, Issue:Serial Attached SCSI RAID Controllers Installation and User's Guide
