If you are removing the last assigned volume from a host cluster, and the host cluster also has hosts with specific assigned volumes, make sure that you remove or move those assignments before removing the last assignment for the host cluster.
If a host cluster, a host, or a host port is assigned to a volume that is registered to the operating system, you must clear this registration before you can remove these nodes.

Steps

From the Manage page, select the storage system with the host connection.
Select Provisioning > Configure Hosts.

The Configure Hosts page opens.
Select the host or host cluster that you want to edit, and then click Unassign Volumes.

A dialog box appears that shows all the volumes that are currently assigned.
Select the check box next to each volume that you want to unassign or select the check box in the table header to select all volumes.
Click Unassign.

Results

The volumes that were unassigned are available for a new assignment.
Until the changes are configured on the host, the volume is still recognized by the host operating system.