IBM ServeRAID, User Reference

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Selecting a RAID level and tuning performance
Disk arrays are used to improve performance and reliability. The amount of
improvement depends on the application programs that you run on the server and
the RAID levels that you assign to the logical drives.
Each RAID level provides different levels of fault-tolerance (data redundancy),
utilization of physical drive capacity, and read and write performance. In addition,
the RAID levels differ in regard to the minimum and maximum number of physical
drives that are supported.
When selecting a RAID level for your system, consider the following factors.
RAID level Data
redundancy Physical drive
capacity
utilization Read
performance Write
performance Built-in
spare
drive Min.
number
of drives Max.
number
of drives
RAID level-0 No 100% Superior Superior No 1 16
RAID level-1 Yes 50% Very high Very high No 2 2
RAID level-1E Yes 50% Very high Very high No 3 16
RAID level-5 Yes 67% to 94% Superior High No 3 16
RAID level-5E Yes 50% to 88% Superior High Yes 4 16
RAID level-00 No 100% Superior Superior No 2 60
RAID level-10 Yes 50% Very high Very high No 4 60
RAID
level-1E0 Yes 50% Very high Very high No 6 60
RAID level-50 Yes 67% to 94% Superior High No 6 60
Physical drive utilization, read performance, and write performance depend on the
number of drives in the array. Generally, the more drives in the array, the better the
performance.
Supported RAID levels
The ServeRAID controllers support RAID level-0, level-1, level-1E, level-5, level-5E,
level-00, level-10, level-1E0, and level-50.
The integrated RAID controllers support RAID level-1 only. The ServeRAID-5i
controller does not support RAID level-5E.
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IBM ServeRAID: User’s Reference, Version 5.10