SLC, MLC, TLC and now QLC. Modern NAND flash storage solutions evolve in the direction of increasing storage density, which is absolutely necessary to bring the cost to a competitive level with old mechanical hard drives. But the clutter of a larger amount of information in the same NAND space comes at the cost of dramatically reducing longevity, which has fallen from an average of 100,000 write / read cycles in the SLC format (1 bit per NAND cell) to less than 1000 write / read cycles for QLC format (4 bits per NAND cell)
Of course, the problem of the reduced edge of NAND flash chips can be greatly improved by advanced "equalization" algorithms of wear, consisting in distributing data tasks as evenly as possible to use the entire available storage space, thus avoiding the use of excessive NAND cells. Directly proportional to the available storage space, the wear is even more insignificant as the capacity of SSD devices reaches higher levels
Organized in NAND 3D modules with up to 64 overlay layers, the new NAND QLC solutions can reach capacities of up to 125GB per module. As technology will be improved, Intel and Micron will deliver 3D NAND modules with up to 96 layers, substantially reducing desktop space on dedicated mobile devices and dedicated SSD devices
Other possible disadvantages posed by QLC NAND solutions are substantial latency enhancement and reduced writing speeds. Inspired by the greater complexity of NAND cell writing operations, the problem has been improved by Intel using a technology called "CMOS under the array" (CuA), allowing parallel writing of multiple flash faces on different layers of the same 3D mode NAND.
Intel has not revealed the exact performance, but emphasizes the benefits of QLC NAND solutions as viewed from the perspective of data center system operators: 41% less busy physical space, up to 3x lower power consumption and costs
The first storage products equipped with QLC NAND technology are supplied by Micron. Based on the 2.5 "format, the Micron 5210 Ion series offers storage capacities between 1.92TB and 7.68TB. According to the manufacturing company, the new SSDs are 2.2x - 3.9x faster than a 1000RPM 4HDD speed drive configuration accessed in RAID-0 mode. But Micron warns against the use of high-volume data-writing applications that could prematurely wear out QLC NAND chips