HP LH4r Integrated HP NetRaid Controller Configuration Guide - Page 22

Chapter 2 RAID Overview RAID 50: Spanning with Distributed Parity In RAID 50 configurations, parity blocks are distributed throughout the logical drive that spans two, three, or four arrays. (RAID 50 is a RAID 5 configuration with array spanning.) If your RAID 50 logical drive has two arrays with four physical drives each, data blocks are written as follows: Stripe 1 Stripe 2 Stripe 3 Disk 1 Block 1 Block 7 Block 13 Array 1 Disk 2 Block 2 Disk 3 Block 3 Block 8 Parity 13-15 Parity 7-9 Block 14 Disk 4 Parity 1-3 Block 9 Block 15 Disk 5 Block 4 Block 10 Block 16 Array 2 Disk 6 Block 5 Disk 7 Block 6 Block 11 Parity 16-18 Parity 10-12 Block 17 Disk 8 Parity 4-6 Block 12 Block 18 RAID 50 Advantages There is no data loss or system interruption due to disk failure, because if one disk fails, data can be rebuilt. Capacity equivalent to only one disk in each array of the RAID 50 logical drive is required to provide redundancy. RAID 50 lets you create large logical drives. You can span up to four arrays containing a maximum of 12 to 16 physical drives. RAID 50 gives good performance if you have a high volume of small, random transfers. RAID 50 Disadvantages Capacity expansion is an offline operation only. Performance is slower than RAID 0 or RAID 10. RAID 50 Summary Choose RAID 50 if you need a large logical drive size, and cost, availability, and performance are equally important. RAID 50 performs best for I/O-intensive, high read/write ratio applications such as transaction processing. 16