LSI MegaRAID SCSI 320-0 Zero-Channel RAID Controller Series 520 Hardware Manual page 39

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)
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 320-0 uses the 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
The MegaRAID SCSI 320-0 controller supports one or two
SCSI channels, with up to 15 SCSI devices on each channel.
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