HP D5970A - NetServer - LCII Configuration Manual page 21

Chapter 2
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:
Disk
1
Stripe
Block
1
1
Stripe
Block
7
2
Stripe
Block
13
3
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.
Array 1
Disk Disk Disk
2 3 4
Block Block Parity Block
2 3
1-3
Block Block Parity Block
8 9
7-9
Block Block Parity Block
14 15
13-15
RAID Overview
Array 2
Disk Disk Disk Disk
5 6 7
Block Block Parity
4 5 6
Block Block Parity
10 11 12
10-12
Block Block Parity
16 17 18
16-18
8
4-6
15