IBM Netfinity ServeRAID-4H Ultra160, User Reference

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RAID level means the sub-logical drive is and the spanned array logical
drive is
00 RAID level-0 RAID level-0
10 RAID level-1 RAID level-0
1E0 RAID level-1E RAID level-0
50 RAID level-5 RAID level-0
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 Hard Disk Drive
Capacity Utilization Read
Performance Write
Performance Built-in Spare
Drive
RAID level-0 No 100% Excellent Excellent No
RAID level-1 Yes 50% Very good Very good No
RAID level-1E Yes 50% Very good Very good No
RAID level-5 Yes 67% to 94% Excellent Good No
RAID level-5E Yes 50% to 88% Excellent Good Yes
RAID level-00 No 100% Excellent Excellent No
RAID level-10 Yes 50% Very good Very good No
RAID level-1E0 Yes 50% Very good Very good No
RAID level-50 Yes 67% to 94% Excellent Good No
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.
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.
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.
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IBM
®
Netfinity
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User’s Reference: ServeRAID
™
-4H Ultra160 SCSI Controller