What’s the difference between SLC, MLC, TLC and 3D NAND? - DIY in 5 Ep 159

Опубликовано 19 ноября 2021, 18:00

NAND flash memory it's in phones, laptops and even the server storing this very video! But not all flash memory is the same. What is NAND flash? What are the different types like SLC, MLC, TLC and 3D NAND? We’ll break down the benefits, limitations, how it works and the different types you’ll find when you are looking to upgrade your SSDs, USB flash drives or memory cards so that you know exactly what you are paying for.

So just what is NAND flash memory?
If you own a Kingston USB flash drive, SD card or SSD, you already own products using NAND flash memory. Unlike DRAM memory, which must be constantly powered to retain information, flash memory retains data even when the power is off. In the past few years, the cost of NAND flash dropped enough to make SSDs, or solid state drives, common as an upgrade over traditional mechanical hard drives as a primary storage method. This is fantastic for a variety of reasons - SSDs have no moving parts in them like a traditional hard drive would, making them faster, more durable so the data is not destroyed if they are dropped, and they consume less energy than a traditional hard drive would, extending battery life etc.

SSD controllers and processors
SSDs have two major components to them, a controller, which serves as the processor for the SSD managing the NAND flash and ensuring that data is spread evenly throughout all physical blocks of the device (which extends the life expectancy) and an array of millions of flash memory cells to hold all the data. Now, here’s where you’ll see different types of NAND like SLC, MLC, etc and these different types of NAND have different characteristics in terms of performance, cost, and endurance.

SLC
SLC or Single-level cell NAND stores 1 bit of information per cell, either a 0 or a 1, and as a result, the data can be written and retrieved faster. Not only is SLC NAND the best performance option out there, it’s also the highest endurance. It’s measured in program-erase or P/E cycles and SLC has about a 100 thousand P/E cycle rating so it will last longer than other types of NAND. The downside here is that it is the most expensive type of NAND and because of this mostly only used for industrial applications and servers and not typically found in consumer products.

MLC
MLC or multi-level cell NAND typically refers to 2 bits of data stored per cell. Because of this higher density, MLC can be produced in larger capacities and offers a nice combo of price to performance to endurance. MLC has about 10 thousand P/E cycles and can often be found in consumer products.

TLC
TLC or triple level cell NAND stores 3 bits per cell, even further reducing cost and increasing capacity, but the tradeoff is that it’s only got 3 thousand P/E cycles. Many consumer products will often use TLC as the most affordable option and it’s now the most dominant SSD technology. There’s also QLC NAND, storing four bits per cell which allows for more affordable, higher capacity storage at a reduced endurance 1 thousand P/E cycles.

3D NAND
We have discussed bits per cell and how higher density storage affects the user experience. Now let’s talk about how those cells are laid out on the drive itself. In traditional 2D NAND, the cells are placed horizontally side by side and engineers can be limited by physical space. Rather than making the cells smaller, which could reduce reliability, 3D NAND was developed, stacking cells vertically as well as horizontally, allowing for more storage, better endurance and lower power consumption. Nowadays, you’ll find 3D NAND used together with MLC, TLC and QLC tech in most higher end drives to get the ideal combo of endurance, capacity and cost. Like the new Kingston FURY Renegade M.2 SSD, using the latest Gen 4x4 NVMe controller and 3D TLC NAND technology to get speeds up to 7,300/7,000 megabytes per second read and write with fantastic consistency in capacities up to 4TB. It’s ideal for gaming, high power users or hardware enthusiasts looking to get performance and endurance.

NAND flash memory provides fast erase and write times at a lower cost per bit, and especially with the rise of the gaming industry and its ever-increasing demands, we’re only going to see this technology evolve.