A memory system and corresponding method of wear-leveling are provided, the system including a controller, a random access memory in signal communication with the controller, and another memory in signal communication with the controller, the other memory comprising a plurality of groups, each group comprising a plurality of first erase units or blocks and a plurality of second blocks, wherein the controller exchanges a first block from a group with a second block in response to at least one block erase count within the group; and the method including receiving a command having a logical address, converting the logical address into a logical block number, determining a group number for a group that includes the converted logical block number, and checking whether group information comprising block erase counts for the group is loaded into random access memory, and if not, loading the group information into random access memory.