Logic MegaRAID SCSI 320-1 RAID Controller User's Guide

RAID 5 3-5

exclusive-or assist make RAID 5 performance exceptional in many

different environments.

Figure 3.3 shows a RAID 5 array with six disk drives.

Figure 3.3 RAID 5 Array

Uses Provides high data throughput, especially for large files. Use

RAID 5 for transaction processing applications, because

each drive can read and write independently. If a drive fails,

the MegaRAID SCSI 320-1 uses the parity drive to recreate

all missing information. Use also for office automation and

online customer service that requires fault tolerance. Use

for any application that has high read request rates but low

write request rates.

Strong Points Provides data redundancy and good performance in most

environments

Weak Points Disk drive performance is reduced if a drive is being rebuilt.

Environments with few processes do not perform as well

because the RAID overhead is not offset by the

performance gains in handling simultaneous processes.

Drives 3 to 15

Segment 1

Segment 7

Parity (9–12)

Segment 2

Segment 8

Segment 3

Segment 9

Parity (5–8)

Segment 4

Segment 10

Disk 1 Disk 2 Disk 3 Disk 4 Disk 5 Disk 6

Segment 5

Segment 11

Parity (1–4)

Segment 6

Segment 12

Data Flow

Note: Parity is distributed

across drives in the array.

MegaRAID Controller