A plurality of storage drives, for managing data. includes: transmitting a first data update command which specifies a first address, and first new data to a first storage drive included in the plurality of storage drives; updating a sequence number of the first address managed in the first storage drive in response to the first data update command; transmitting a first redundant data update command which specifies a second address of old redundant data, data for updating the old redundant data, and the updated sequence number, to a second storage drive which stores the old redundant data associated with the first address and which is included in the plurality of storage drives; updating the old redundant data based on the data for updating the old redundant data; and updating a sequence number of the second address managed in the second storage drive according to the updated sequence number.