FTL algorithm using warm block technique for QLC+SLC hybrid NAND flash memory

When applying the existing flash translation layer technique to a mixed NAND flash storage device composed of Quad Level Cell and Single Level Cell, because the characteristics of a semiconductor chip are not taken into consideration, the data are stored indiscriminately, and thus the performance and stability are not guaranteed. Therefore, this study proposes a flash translation layer algorithm using the warm block technique in a NAND flash storage device that combines a large capacity Quad Level Cell and a high performance Single Level Cell. The warm block technique avoids overloading of the read/write/erase operations in the Quad Level Cell flash memory by efficiently placing hot data that are frequently updated on a long-living Single Level Cell. It was confirmed experimentally that the lifetime extension and performance of hybrid NAND flash memory are improved using the warm block technique.