Selecting A Raid Level And Performance Tuning - IBM Netfinity ServeRAID-3H Installation And User Manual

Then, create a logical drive (labeled as 1) within the
array.
Notice that the distributed spare drive is the free space
(labeled as 2) below the logical drive.
The data is striped across the drives, creating blocks in
the logical drive.
The storage of the data parity (denoted by
and it shifts from drive to drive as it does in RAID
level-5.
Notice that the spare drive is not striped.
If a physical drive fails in the array, the data from the
failed drive is compressed into the distributed spare
drive. The logical drive remains RAID level-5E.
When you replace the failed drive, the data for the
logical drive decompresses and returns to the original
striping scheme.
Note: The ServeRAID Manager program Express configuration does not default to RAID level-5E. If you
have four physical drives, Express configuration defaults to RAID level-5 with a hot-spare drive.

Selecting a RAID level and performance tuning

When selecting a RAID level for your system, consider the following:
RAID level Data
Redundancy
RAID level-0 No
RAID level-1 Yes
RAID level-1E Yes
RAID level-5 Yes
RAID level-5E Yes
1 Depending on the number of physical drives in the array.
2 Performance depends on the number of drives in the array. Generally, the more drives in the array, the better your performance.
10
IBM ServeRAID-3H, ServeRAID-3HB, and ServeRAID-3L, Controllers
x
*
) is striped,
x
x
Hard Disk Read
Drive Capacity Performance
Utilization
100% Excellent
50% Very Good
50% Very Good
67% to 94% 1 Excellent
50% to 88% 1 Excellent
1
*
4
*
7 8
1
*
3
*
5 6
7
*
9
*
Write
Performance
Excellent
Very Good
Very Good
2 Good 2
2 Good 2
1
2
2 3
5 6
9
*
2
4
*
8
Built-in Spare
Drive
No
No
No
No
Yes