MSI X2-109 v1 - Manual (Page 24)

1-8 Overview
Version 2.0 Copyright © 2006 by LSI Logic Corporation. All rights reserved.
RAID 5 addresses the bottleneck issue for random I/O operations.
Because each drive contains both data and parity, numerous writes can
take place concurrently.
Figure 1.3 shows a RAID 5 array with six disk drives.
Figure 1.3 RAID 5 Array
Uses
Provides high data throughput. Use RAID 5 for transaction
processing applications because each drive can read and
write independently. If a drive fails, the RAID controller 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, high read rates, and good
performance in most environments. Provides redundancy with
lowest loss of capacity.
Weak Points
Not well suited to tasks requiring lot of small writes. Suffers
more impact if no drive cache is used (clustering). Disk drive
performance will be reduced if a drive is being rebuilt or a
background initialization is in progress. 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
Three to eight
Segment 1
Segment 7 Segment 2
Segment 8 Segment 3
Segment 9 Segment 4
Segment 10
Segment 5
Parity (6-10)
Parity (11–15)
Parity (1-5)
Segment 6
Note: Parity is distributed across all drives in the array.
Segment 12 Segment 15 Segment 11 Segment 14 Segment 13
Segment 19
Segment 25 Segment 20
Segment 23
Segment 18
Segment 21
Segment 16
Segment 22
Segment 17
Parity (21-25)
Parity (26–30)
Parity (16-20)
Segment 24
Segment 30 Segment 27 Segment 29 Segment 26 Segment 28