A controller for managing at least one MLC non-volatile memory space including at least one MLC non-volatile memory element and at least one SLC non-volatile memory space including at least one SLC non-volatile memory element. The controller is adapted to determine if a range of addresses listed by an entry and mapped to the at least one MLC non-volatile memory element fails a data integrity test performed at the controller based upon received data retained at the controller and which received data is stored in the at least one MLC memory element as stored data. In the event of such a failure, the controller remaps said entry to an the at least one SLC non-volatile memory element.