Users guide

Intel® RAID Software User Guide 12
Table 3 provides an overview of RAID 5.
Table 3. RAID 5 Overview
Figure 3. RAID 5 – Data Striping
with Striped Parity
2.2.4 RAID 6 - Distributed Parity and Disk Striping
RAID 6 is similar to RAID 5 (disk striping and parity), but instead of one parity block per
stripe, there are two. With two independent parity blocks, RAID 6 can survive the loss of
two disks in a virtual disk without losing data.
Table 4 provides an overview of RAID 6.
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 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, an
d good performance in most
environments. Provides redundancy with lowest loss of capacity.
Weak Points
Not well suited to tasks requiring lot of
writes. Suffers more impact if no
cache is used (clustering). If a drive is being rebuilt, disk drive
performance is reduced. 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 32
RAID Adapter
ABCDEF
A
C
P3
B
P2
E
Data Striping &
Striped Parity
RAID 5
Available Capacity
N=# disks
C = Disk Capacity
Available Capacity =
(N*C)(N-1) /N
P1
D
F
RAID 5