Which NetApp ONTAP option enables automatic host-side space management for a LUN?

The space-allocation option enables ONTAP support for SCSI thin-provisioning functions and allows compatible SAN hosts to manage and reclaim unused LUN space. When space allocation is enabled, ONTAP can communicate storage-space conditions to the host and support host-initiated space reclamation through mechanisms such as SCSI UNMAP. NetApp specifically states that enabling space allocation allows SAN hosts to reclaim storage that is no longer being used. space-reserve controls whether physical capacity is reserved for the LUN but does not provide host-side reclamation. resize relates to changing storage size, and alua controls asymmetric path behavior rather than capacity management. Current ONTAP releases enable space allocation by default for many newly created SAN objects. Relevant SAN ONTAP topics include LUN thin provisioning, SCSI UNMAP, space reclamation, and LUN space-allocation configuration.