A memory device comprises a nonvolatile memory device and a controller. The nonvolatile memory comprises a first memory area comprising single-bit memory cells and a second memory area comprising multi-bit memory cells. The controller is configured to receive a first unit of write data, determine a type of the first unit of write data, and based on the type, temporarily store the first unit of write data in the first memory area and subsequently migrate the temporarily stored first unit of write data to the second memory area or to directly store the first unit of write data in the second memory area, and is further configured to migrate a second unit of write data temporarily stored in the first memory area to the second memory area where the first unit of write data is directly stored in the second memory area.