The invention relates to a method, a non-transitory computer-readable storage medium and an apparatus for data access in response to a host discard command. The method includes: allocating space in a random access memory (RAM) for an expanded discard table; receiving the host discard command from a host side; appending new entries each including one first logical address to the expanded discard table; and setting a start-address register and/or an end-address register in a performance engine for redefining an address range in the RAM that stores the expanded discard table, thereby enabling the performance engine to search the expanded discard table in the address range in the RAM for determining whether a specific logical address of user data is no longer used.