Larger disk sizes are also possible, since the maximum number of blocks is limited by a fixed bit-width block number. However, with larger block sizes, disks with many small files will waste space, since each file must occupy at least one block. Because of this, BSD added "block-level fragmentation", also called block suballocation, tail merging, or tail packing, where the last partial block of data from several files may be stored in a single "fragment" block instead of multiple mostly empty blocks .