SK hynix says it has begun mass production of its 321-layer 2-terabit (Tb) quad-level cell (QLC) NAND flash memory, which marks the first implementation of QLC NAND to employ more than 300 layers. Notably, SK hynix demoed 321-layer 1tb triple-level cell (TLC) chips a couple of years ago. The upshot of “setting a new benchmark in NAND density”