LSI MegaRAID SCSI 320-2 RAID Controller Series 518 Hardware Manual page 41

Figure 3.3 RAID 5 Array
Note: Parity is distributed
across drives in the array.
Disk 1
Segment 1 Segment 2
Segment 7 Segment 8
Parity (9–12)
exclusive-or assist make RAID 5 performance exceptional in many
different environments.
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 320-2 uses the distributed
parity data 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 30
Figure 3.3 shows a RAID 5 array with six disk drives.
MegaRAID Controller
Disk 2
Segment 3
Segment 9
Parity (5–8)
RAID 5
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
Data Flow
Disk 3 Disk 4
Segment 4
Segment 10
Disk 5
Segment 5 Segment 6
Segment 11 Segment 12
Parity (1–4)
Disk 6
3-5