Selecting A Raid Level And Performance Tuning; Drive State Descriptions - IBM Netfinity ServeRAID-4H Ultra160 User Reference

RAID level
00
10
1E0
50
With RAID level-10, 1E0, and 50, if one of the physical drives fails in a sub-logical
drive, the ServeRAID controller switches read and write requests to the remaining
functional drives in the sub-logical drive. With RAID level-00, a physical drive failure
within the sub-logical drive results in loss of data.

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
RAID level-00 No
RAID level-10 Yes
RAID level-1E0 Yes
RAID level-50 Yes

Drive state descriptions

This section provides descriptions of the physical and logical drive states.
Physical drive state descriptions
The following table provides descriptions of the valid physical drive states.
1. Disk utilization, read, and write performance depend on the number of drives in the array. Generally, the more drives in the array,
the better your performance.
® ®
10
IBM Netfinity User's Reference: ServeRAID
means the sub-logical drive is
RAID level-0
RAID level-1
RAID level-1E
RAID level-5
Hard Disk Drive
Capacity Utilization
100%
50%
50%
67% to 94%
50% to 88%
100%
50%
50%
67% to 94%
Drive State Meaning
Defunct A physical drive in the online, hot-spare, or rebuild state has become
defunct. It does not respond to commands, which means that the
ServeRAID controller cannot communicate properly with the drive.
If a physical drive has become defunct, refer to "Rebuilding a defunct
drive" on page 136.
Hot spare A hot-spare drive is a physical drive that is defined for automatic use
when a similar drive fails.
Online The drive is online. It is functioning properly and is part of an array.
Rebuilding The drive is being rebuilt.
For more information on rebuilding a drive, refer to "Rebuilding a defunct
drive" on page 136.
™
-4H Ultra160 SCSI Controller
and the spanned array logical
drive is
RAID level-0
RAID level-0
RAID level-0
RAID level-0
Read Write
Performance Performance
Excellent Excellent
Very good Very good
Very good Very good
Excellent Good
Excellent Good
Excellent Excellent
Very good Very good
Very good Very good
Excellent Good
Built-in Spare
Drive
No
No
No
No
Yes
No
No
No
No