For a host or host cluster to send I/O to a volume, you must assign the volume to the host or host cluster.

You can select a host or host cluster when you create a volume or you can assign a volume to a host or host cluster later. A host cluster is a group of hosts. You create a host cluster to make it easy to assign the same volumes to multiple hosts.

Assigning volumes to hosts is flexible, allowing you to meet your particular storage needs.

When volumes are created, logical unit numbers (LUNs) are assigned automatically. The LUN serves as the "address" between the host and the controller during I/O operations. You can change LUNs after the volume is created.