After deleting a LUN, an administrator notices that the space does not show as available.

After deleting a LUN, if the space does not show as available, performing space reclamation is necessary. Space reclamation involves identifying and reclaiming unused space on the storage system, making it available for new data. This process ensures that the deleted LUN's space is properly freed up and reflected in the available storage capacity.

For more details, refer to:

NetApp Documentation on Space Reclamation

NetApp Community on Free Space Reclamation