IBM Netfinity ServeRAID-4H Ultra160, Справочник пользователя

Страница: 20 / 192

RAID level-5 offers both data protection and increased throughput. RAID level-5
gives you higher capacity than RAID level-1, but RAID level-1 offers better
performance.
RAID level-5 requires a minimum of 3 drives and, depending upon the level of
firmware and the stripe-unit size, supports a maximum of 8 or 16 drives.
The following illustration is an example of a RAID level-5 logical drive.
Start with four physical drives.
Create an array using three of the
physical drives, leaving the fourth as a
hot-spare drive.
Then, create a logical drive within that
array.
The data is striped across the drives,
creating blocks.
Notice that the storage of the data
parity (denoted by
.
) also is striped,
and it shifts from drive to drive.
A parity block (
.
) contains a
representation of the data from the
other blocks in the same stripe. For
example, the parity block in the first
stripe contains data representation of
blocks 1 and 2.
1 2
3
5
7
4
6
8
2
*
*
*
*
6
IBM
®
Netfinity
®
User’s Reference: ServeRAID
™
-4H Ultra160 SCSI Controller