A data storage device includes a memory device including multiple memory blocks corresponding to multiple sub-regions and a memory controller. The memory controller accesses the memory device and updates content of a read count table in response to a read command with at least one designated logical address issued by a host device. Each field of the read count table records a read count associated with one sub-region and the content of the read count table is updated by increasing the read count associated with the sub-region that the designated logical address belongs to. The memory controller selects at least one sub-region to be rearranged according to the content of the read count table and performs a data rearrangement procedure to move data of logical addresses belonging to the selected at least one sub-region to a first memory space of the memory device having continuous physical addresses.