IBM Midrange System DS4000 Series Hardware Manual page 231

You can continue creating other partitions or host groups, you should know that even though
you can create multiple partitions, you can only map logical drives to partitions up to the
maximum number allowed by your specific system and premium feature configuration. Check
your storage subsystem for the allowed number of partitions by selecting, in the Subsystem
Management view, Storage Subsystem  Premium Features, and review the information
presented, as shown in Figure 4-80.
:
Figure 4-80 Partitions allowed
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Chapter 4. IBM System Storage DS planning and configuration