A control device is configured to receive a first write request of first data, calculate a first parity of the first data, store the first data and the first parity into a storage region so that the first data is stored redundantly, identify a certain area which has a possibility that a write process to the certain area is requested after a read process from the certain area is requested, receive a read request of the first data stored in the certain area, read the first data and the first parity, and store the first data and the first parity into a memory, receive a second write request of a second data, calculate a second parity based on the second data, the first data stored in the memory and the first parity stored in the memory, and store the second data and the second parity into the storage region.