A data storage device includes a memory device including multiple memory blocks corresponding to multiple logical units and a memory controller. The memory controller accesses the memory device and updates content of an activated count table in response to a command issued by a host device. One or more sub-regions to be activated are identified in the command. The activated count table includes a plurality of fields each recording an activated count associated with one sub-region. The memory controller updates content of the activated count table by increasing one or more activated counts associated with the one or more sub-regions identified in the command. The memory controller further selects at least one sub-region according to the content of the activated count table and performs a data rearrangement procedure to move data of the selected at least one sub-region to a first memory space having continuous physical addresses.