IBM Midrange System DS4000 Series Hardware Manual page 210

You can define logical drives from unconfigured capacity or from free capacity already
available in previously defined arrays on the storage system:
When you create a logical drive from unconfigured capacity, you create an array by first
choosing the RAID type, and so on, and then the needed logical drives.
If an array is not created, you can still create a logical drive, but the Storage Manager will
direct you to create the array first.
If there is free capacity on a previously defined array, you can create additional logical
drives using that free capacity.
The example that follows assumes that there is unconfigured capacity on the DS5000 storage
subsystem. Note that the unconfigured capacity for Fibre Channel and SATA disks are
grouped separately. This procedure illustrates the most common steps to follow in setting up
a logical drive from unconfigured drives:
1. In the Subsystem Management window (Figure 4-57), right-click the unconfigured
capacity for the selected drive type. Because we have selected unconfigured capacity, we
first create an array option. Choosing Create Logical Drive causes a window to open that
requests that you create the array first. Select Create Array.
Figure 4-57 Create logical drive from unconfigured capacity
This action starts the wizard for creating the array first and then the logical drives. The first
window of the wizard is an introduction to the process. It displays the available
unconfigured capacity for the type of disks selected. Read the introduction and then click
Next in order to proceed.
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IBM Midrange System Storage Hardware Guide