The spacemon snap_reclaimable command displays the space that can be reclaimed by deleting a Snapshot copy.
sdcli spacemon snap_reclaimable -f Storage_System -vn Volume_Name -s snapshot
Storage_System is the name of the storage system on which the volume exists.
Volume_Name is the name of the volume on which the Snapshot copy resides.
snapshot is the name of the Snapshot copy for which you want to view reclaimable space.