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This soft copy for use by IBM employees only.
Note
It is not necessary to define multiple logical drives of the same RAID
level. You can partition these logical drives the same way you partition a
real disk when you install the operating system.
8. Select Exit to leave this menu.
9. Select Yes to save the changes.
Figure 40 shows an example of a completed array definition that includes
two logical drives: one 400MB RAID-5 array and one 2925MB RAID-1 array.
IBM RAID Controller Configuration Ver 2.12
Adapter in Slot 1
┌───────────┐ ┌───────────┐
│┌─────────┐│ │┌─────────┐│
│└Ch 1┘│ │└Ch 2┘│
│┌─Bay │ │┌─Bay │
││ Array ──┐│ ││ Array ──┐│
│ ┌─────┐ │ │ ┌─────┐ │
│1 └ ┘ │ │1 └ ┘ │
│ ┌─────┐ │ │ ┌─────┐ │
│2 └ ┘ │ │2 └ ┘ │
│ ┌─────┐ │ │ ┌─────┐ │
│3 └ HSP ┘ │ │3 └ ┘ │
│ ┌─────┐ │ │ ┌─────┐ │
┌───────────────┬───────────────────────────┐ │4 └ ONL ┘ A│ │4 └ ┘ │
│Array Arrays │ Log Size RAID Date │ │ ┌─────┐ │ │ ┌─────┐ │
│ID Size (MB)│ Drv (MB) Level Created │ │5 └ ONL ┘ A│ │5 └ ┘ │
├───────────────┼───────────────────────────┤ │ ┌─────┐ │ │ ┌─────┐ │
│ A 6450 │ A0 400 RAID-5 08/24/95 │ │6 └ ONL A│ │6 └ ┘ │
│ │ A1 2925 RAID-1 08/24/95 │ │ ┌─────┐ │ │ ┌─────┐ │
│ │ │ │7 └ ┘ │ │7 └ ┘ │
└───────────────┴───────────────────────────┘ └───────────┘ └───────────┘
Figure 40. RAID Configuration Program - Result
2.5.1.6 Setting the Write Policy
Now that the logical drives have been created, you may wish to change the write
policy for these drives.
If you want to change the write policy:
1. Select Advanced functions from the main menu.
2. Select Change write policy.
3. Use the up and down arrow keys to select the logical drive.
4. Press Enter to toggle the write policy.
The different options are as follows:
•
WB for Write-Back
In the write-back mode, the completion status is sent before the data is
actually written to the drives. While this mode will yield higher performance,
it is critical to protect the DASD power to ensure the write operations
actually complete, since the processor thinks the operation has been
completed.
•
WT for Write-Through
Chapter 2. Hardware Configuration 47