a plurality of first memory devices each including a plurality of zones on which sequential writing is performed;

a second memory device including a plurality of parity zones; and

a memory controller configured to:

allocate to a parity group, first zones included in the respective first memory devices and a first parity zone storing parity data for data stored in the first zones, the first parity zone being one of the parity zones in the second memory device,

release from the parity group, a first zone invalidated among the first zones by writing new data into a target zone different from the invalidated first zone among the zones included in the first memory device including the invalidated first zone, and

allocate the target zone to the parity group.