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This soft copy for use by IBM employees only.
•Rebuild Priority
This parameter sets the priority of the execution order of the rebuild I/O requests with respect to the system I/O requests. The rebuild priority can be changed without affecting data in the logical drive.
•Parity Placement
Parity placement defines how parity is placed in the disk array with respect to the data. Figure 32 shows the differences between left symmetric and right asymmetric parity placement.
Right Asymmetric (RA)
Disk Disk Disk Disk 1 2 3 4
PP0 AAA BBB CCC
DDDPP1 EEE FFF GGG HHH PP2 III JJJ KKK LLL PP3
Left Symmetric (LS)
Disk Disk Disk Disk 1 2 3 4
AAABBB CCC PP0 EEE FFF PP1 DDD III PP2 GGG HHH PP3 JJJ KKK LLL
Figure 32. Parity Placement in a RAID Subsystem
The default value is right asymmetric. In some situations, you may want to try Left Symmetric to improve performance.
Note: Once a parity placement scheme is chosen and data is stored in the logical drives, it cannot be changed without destroying data in the logical drives.
•
Normally the IBM
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Note: The
2.5.1.3 Defining a Hot-Spare Disk
After selecting Create/Delete Array from the main menu of the IBM RAID Configuration program, the following panel appears:
Chapter 2. H a r d w a r e Configuration 41