A method for performing data-compression management in a storage server may include: receiving data from a host device; performing entropy detection on a plurality of sets of partial data to generate entropy detection values of the plurality of sets of partial data, respectively; classifying the plurality of sets of partial data according to the entropy detection values of the plurality of sets of partial data, respectively, to perform data compression on at least one portion of the plurality of sets of partial data through a plurality of data compression modules, respectively, wherein the plurality of data compression modules correspond to different compression capabilities, respectively; and storing the plurality of sets of partial data into at least one storage device of the storage server and recording address mapping information of the plurality of sets of partial data, respectively. An associated apparatus is also provided.