Appendix C: Selecting the Best RAID Level ● 165RAID 50 Logical DrivesA RAID 50 logical drive is built from at least six disk drives configured as two or more RAID 5logical drives, and stripes stored data and parity data across all disk drives in both RAID 5logical drives. (For more information, see RAID 5 Logical Drives on page 163.)The parity data provides data protection, and striping improves performance. RAID 50 logicaldrives also provide high data transfer speeds.Drive segment size is limited to the size of the smallest disk drive in the logical drive. Forexample, three 250 GB disk drives and three 400 GB disk drives comprise two equal-sizedRAID 5 logical drives with 500 GB of stored data and 250 GB of parity data. The RAID 50logical drive can therefore contain 1000 GB (2 x 500 GB) of stored data and 500 GB of paritydata.In this example, P represents the distributed parity data.RAID 5BRAID 50 LogicalDrive=1000 GBplus ParityRAID 5AEach RAID 5 Logical Drive has500 GB Data Storage250 GB Parity DataDrive 1250 GBDrive 2250 GBDrive 3250 GB Drive 4400 GBDrive 5400 GBDrive 6400 GB1, 5, P 3, P, 9 P, 7, 11 2, 6, P 4, P, 10 P, 8, 12 Total UnusedSpace = 150 GB
