A storage device and a method for operating the storage device are provided. A storage device includes processing circuitry configured to write multi-stream data on a non-volatile memory; generate parity data of the multi-stream data and/or intermediate parity data upon which the parity data is based; store the parity data and/or the intermediate parity data in a first memory; and perform a data swap between the first memory and a second memory, wherein a number of slots of a plurality of slots in the first memory is based on a number of execution units of program buffering of the non-volatile memory.