A non-volatile memory includes a plurality of blocks of physical memory, including a target block and at least one source block containing at least some valid data and some invalid data. Responsive to determining to perform garbage collection for the non-volatile memory, the controller transfers valid data from the at least one source block to the target block. The controller ends garbage collection on the at least one source block with at least some valid data present in the at least one source block and all interfaces of the target block closed at the boundary of independent layers. In at least some embodiments, the target block may be configured to store more bits per cell than the at least one source block.