HP A7143A RAID160 SA Controller Support Guide

RAID Technology Overview
HP RAID160 SA Controller Supported RAID Configurations
Chapter 124
This method is most useful when data loss is unacceptable, but cost must
also be minimized. The probability that data loss will occur when arrays
are configured with RAID ADG is less than when they are configured
with RAID 5 (see Appendix A, “Probability of Logical Drive Failure,” on
page 133).
Figure 1-8 Advanced Data Guarding (RAID ADG)
Advantages
• High read performance
• High data availability—any two disks can fail without loss of critical
data
• More disk drive capacity usable than with RAID 1+0—parity
information requires only the storage space equivalent to two
physical disks
Disadvantages
The only significant disadvantage of RAID ADG is a relatively low write
performance (lower than RAID 5), due to the need for two sets of parity
data.
B1
B3
P5,6
Q7,8
B2
B7
P3,4
Q5,6
B5
B8
P1,2
Q3,4
B4
B6
P7,8
Q1,2