Management information is provided to control a storage including storage-areas so that each storage-area includes a set of data-areas allocated from each storage-area and each set of data-areas has a data-area size that is a different integer multiple of an access unit of the storage. Logical address information stores information identifying a data-area into which target-data obtained by compressing data has been written, in association with a logical address of the data. Upon reception of the data and the logical address of the data, the apparatus identifies the management information corresponding to a data-area size greater than or equal to a size of the target-data, writes the target-data into an unused data-area of one of the sets of data-areas corresponding to the identified management information, and stores, in the logical address information, information identifying a physical address of the unused data-area in association with the logical address of the data.