A storage system having high reliability and IO processing performance is realized. The storage system includes: a first arithmetic unit configured to receive an input and output request and perform data input and output processing; a first memory connected to the first arithmetic unit; a plurality of storage drives configured to store data; a second arithmetic unit; and a second memory connected to the second arithmetic unit. The first arithmetic unit instructs the storage drive to read data, the storage drive reads the data and stores the data in the second memory, the second arithmetic unit stores the data stored in the second memory in the first memory, and the first arithmetic unit transmits the data stored in the first memory to a request source of a read request for the data.