Storage device and storing method

Abstract

To enable a capacity of an entire storage device to be kept by adding a flash drive or a flash module in the flash drive for a flash memory that has a failure, even if the storage device using the flash memory has a failure in its part such as a part of flash memory chip has a failure, for example, the flash memory chip has run out of its lifetime. In a storage deviceequipped with two or more memory device unitswith a plurality of semiconductor memory devices, each of which has a functional capacity unitsmaller than a capacity of an entire semiconductor memory device and has a writing lifetime for each functional capacity unit, only a functional capacity unit whose writing lifetime is run out to be determined as unable to be written is substituted by a functional capacity unit in a memory device of the other memory device unit to keep a predetermined capacity of the entire device.