HP LH4r Integrated HP NetRaid Controller Configuration Guide - Page 21

Chapter 2 RAID Overview RAID 30: Spanning with Dedicated Parity Drives In RAID 30 configurations, parity blocks provide redundancy to a logical drive that spans two, three, or four arrays. (RAID 30 is a RAID 3 configuration with array spanning.) If your RAID 30 logical drive has two arrays with four physical drives each, data blocks are written as follows: Array 1 Array 2 Stripe 1 Stripe 2 Stripe 3 Disk 1 Block 1 Block 7 Block 13 Disk 2 Block 2 Block 8 Block 14 Disk 3 Block 3 Block 9 Block 15 Disk 4 Parity 1-3 Parity 7-9 Parity 13-15 Disk 5 Block 4 Block 10 Block 16 Disk 6 Block 5 Block 11 Block 17 Disk 7 Block 6 Block 12 Block 18 Disk 8 Parity 4-6 Parity 10-12 Parity 16-18 RAID 30 Advantages There is no data loss or system interruption due to disk failure, because if one disk fails, data can be rebuilt. Only one disk in each array of a RAID 30 logical drive is required to provide redundancy. HP NetRAID firmware optimizes RAID 30 data flow for long, serial data transfers such as video or imaging applications. RAID 30 lets you create large logical drives. You can span up to four arrays containing a maximum of 12 to 16 physical drives. RAID 30 Disadvantages Capacity expansion is an offline operation only. Performance is slower than RAID 0 or RAID 10. RAID 30 Summary Choose RAID 30 if you need a large logical drive size, and cost, availability, and performance are equally important. RAID 30 performs best when long, serial transfers account for most of the reads and writes. 15