storing first compressed objects, which are obtained by compressing user data stored in the volatile memory in a page unit, in an empty area of the volatile memory;

moving a second compressed object, which satisfies a specified condition, from among the first compressed objects to at least one temporary buffer set in the volatile memory;

based on a first temporary buffer from among the at least one temporary buffer being filled to a specified size or more, registering third compressed objects stored in the first temporary buffer in a write list in units of a compressed object group; and

based on a number of compressed object groups registered in the write list being more than or equal to a specified value, moving the compressed object groups to the non-volatile memory in compressed states.