A memory system may comprise: a memory device including a plurality of memory dies; and a controller including a first memory, Wherein the controller may store data segments of user data, corresponding to a plurality of commands received from a host, in the first memory, controls the memory device to sequentially store the data segments in the memory dies through interleaving, may update map segments of map data corresponding to storage of the data segments in the memory dies, may store the map segments in the first memory, controls the memory device to store the map segments stored in the first memory in the memory dies, and may assist the host in storing the map segments, stored in the first memory, in a second memory in the host.