Installation and configuration of the HP NetRAID, NetRAID-1 and NetRAID 3Si Adapters

Chapter 2 RAID Overview
21
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
Disk
1
Disk
2
Disk
3
Disk
4
Disk
5
Disk
6
Disk
7
Disk
8
Stripe
1
Block
1
Block
2
Block
3
Parity
1-3
Block
4
Block
5
Block
6
Parity
4-6
Stripe
2
Block
7
Block
8
Block
9
Parity
7-9
Block
10
Block
11
Block
12
Parity
10-12
Stripe
3
Block
13
Block
14
Block
15
Parity
13-15
Block
16
Block
17
Block
18
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 Series adapter 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 24 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.