HP A7143A RAID160 SA Controller Support Guide

RAID Technology Overview

HP RAID160 SA Controller Supported RAID Configurations

Chapter 120

• Cannot use an online spare

• Can only preserve data by backing it up to external disk drives

NOTE The original Berkeley RAID study only defined levels 1 through 5. RAID

Level 0 was conceived later, but is not considered to be a “true” RAID,

because it does not provide any fault tolerance.

RAID 1—Disk Drive Mirroring

In this configuration, only two physical disks are present in the array.

Data is duplicated from one disk onto the other disk creating a mirrored

pair of disk drives, but there is no striping of data (see Figure 1-5, “Disk

Drive Mirroring of P1 onto P2 (RAID 1),”).

Figure 1-5 Disk Drive Mirroring of P1 onto P2 (RAID 1)

Advantages

• No data loss or interruption of service, if a disk fails

• Fast read performance - data is available from either disk

Disadvantages

• Cost is high - 50% of disk space is allocated for data protection

P1 P2