SSD NAND – SLC, MLC, TLC, and QLC
The first differentiator for SSD relates to the NAND flash, which would either be SLC (Single Level Cell), MLC (Multi Level Cell), TLC (Triple Level Cell) or QLC (Quad Level Cell). The difference between the four is the amount of data stored per cell – with SLC it's 1-bit per cell, with MLC it's 2-bits per cell, with TLC its 3 bits per cell, and with QLC its 4 bits per cell. These differences in design impact performance, MDF, storage capacity, and most importantly price point, all of which are factors that determine which type of NAND is best for which type of application.
In general, because Single Level Cell (SLC) drives are less complex, they have longer MDF (10 times that of MLC and 20 times that of TLC), less storage capacity, better performance, and higher cost than other NAND. MLC, TLC, and now QLC NAND, however, offer far greater potential for SSDs because they deliver very good performance, high durability, low power consumption, and have the advantage of being able to store more bits per cell which increases capacity and lowers the cost per gigabit making SSDs more affordable. All of these advantages are driving SSD growth in all markets, including data centers, high performance computing, mobile computing, and so on.
3D NAND and V-NAND
As the demand for greater capacity in SSDs continued to grow, the traditional planar NAND was reaching its scaling limits, making it increasingly difficult to meet the need of more storage. With that came the introduction of 3D NAND, or V-NAND as it is called by Samsung, which uses an innovative technology to stack the NAND cells vertically to provide 3X the capacity. 3D NAND or V-NAND incorporates either MLC, TLC, or QLC NAND using the x,y and z axis to expand vertically.
Click here for a short video showing how Intel 3D NAND Technology Transforms the Economics of Storage.