A control device stores information associating each of a plurality of physical areas with a plurality of logical areas. The control device respectively stores a plurality of first user data included in a first stripe and a first parity data created on the basis thereof in each of the plurality of physical areas, and, in accordance with receiving a write request for updated user data that updates the user data, which is stored in a first physical area, for a first logical area associated with the first physical area, creates a second parity data on the basis of a data group formed using the updated user data and a plurality of second user data that differs from the plurality of first user data.