SSD TLC or SLC?

Hey, it was no problem.

First, this will be a relatively fast explanation, if you want more depth, there will be lots you can find online.

SSDs store all their information in cells, SLC - single level cell - stores a single bit of information (Literally, either a 0 or a 1). MLC -multi-level cell - stores 2 bits, and TLC - triple level cell - stores 3 bits. You may think that storing more information means you can get more back with a single read, but actually, you get the same amount. That is to say, when you read from the cell, you can read 1 of the bits, and only 1, which means 1 read gets all the information stored in an SLC, 2 reads for MLC, and 3 reads for TLC. This is important more because of how a read is handled. To get data, a voltage is applied to the cell, which causes to read a certain way (In this case, its characteristics determine the value. This is were my own knowledge is reaching its limit, but I think a it's something like resistance, so a 0 would be less, and a 1 is more resistance. Then just measure the voltage after it passes through that resistance and you will know which value the cell contained). That's great for SLC, but how does MLC work? An MLC can be in 4 states, 00, 01, 10, and 11. The SSD controller needs to apply a particular voltage so that it reads only 1 of those bits. Basically, it needs to differentiate between them, I think because 10 and 01 would look the same if you didn't. Keep in mind that you need to apply voltage to do a write as well, and I've only mentioned reading.

TLC is the same concept at MLC, but with 000, 001, 010, 011, 100, 101, 110, and 111 (8 states). This gets a lot more difficult to handle. As a drive wears out, the max voltage you can apply basically shrinks. With SLC, the shrinking isn't much of an issue, because of how much overhead you have. People used to be worried about MLC drives and their shrinking voltage / wear, but that's basically gone now. TLC has renewed that worry, but I personally think we're at the stage where it's not much of an issue anymore. Going to QLC (Quad level cell, never heard of it but just the logical extension) would mean the controller has to deal with 16 states (It doubles every time), and that I think it's out of reach. It was much easier to make VNAND (Samsung) or 3D NAND (I think everyone else).

There is a lot more going on with what an SSD is doing, and I am sure I can explain more if you have more questions, but you just asked about MLC and TLC. By the way, there are eMLC, and super MLC and other buzz word things. Super MLC is ordinary MLC, but instead of putting 2 bits per cell, like it was designed for, you just put 1. Why do that? The cell itself needs to be made with SLC, MLC, or TLC in mind, it is more than just the controller that is doing it, but most people have stopped making SLC wafers. Super MLC has, to my understanding, all the benefits of SLC at the price point (approximately) of SLC. However, it will pretty much only be found in the enterprise, because only they need that level of endurance. I don't remember what eMLC is, but you can Google that.