A storage apparatus connectable to another storage apparatus so as to copy the data thereto, for providing a first virtual volume including at least a first block, includes at least a storage unit having storage areas, each storage area being allocatable as a one of the first blocks; a memory storing information for indicating a relationship between each first block and each the storage area, at least one of the storage areas being allocated to the at least one of the first blocks according to a usage pattern of the first virtual volume; and a controller configured to receive an instruction for copying data, determine whether each first block is allocated to any of the storage areas or not in reference to the information, transmit data indicating that one of the first blocks is unallocated to any of the first storage areas on the basis of the determination.