Figure 4. Raid 5 Configuration Example - 3Ware 3W-6800 User Manual

Storage switch

Table of Contents

3ware Escalade Storage Switch User Guide

RAID 5 arrays optimize performance, fault tolerance,

high capacity and storage efficiency

The RAID 5 configuration features the data striping of RAID 0

combined with the parity of RAID 4. Using a simple parity (exclu-

sive OR) function, RAID 5 can tolerate the loss of one drive. Parity

information is distributed across all drives rather than being con-

centrated on a single disk (see Figure 4). This avoids throughput

loss due to contention for the parity drive. You can use hot spares to

rebuild a failed drive "on-the-fly".

RAID 5 capacity = size of smallest drive

In addition, the array's storage efficiency increases with the number

of disks; from 66.7 % for 3 drives to 87.5 % for 8 drives: storage

efficiency = (number of drives -1)

Unlike all other RAID configurations that offer data striping, except

for RAID 1, RAID 5 stripe size is limited to 64k.

Note:

having less than 3 drives.