WEBVTT 00:00:00.000 --> 00:00:04.480 Eight terabytes of solid state storage for less than 500 bucks? 00:00:04.480 --> 00:00:09.160 Back in 2009, you would have paid that much for a mere 32 gigs of space. 00:00:09.160 --> 00:00:15.480 So why is it that you can get 250 times the space for the same price a mere 14 years later? 00:00:15.480 --> 00:00:18.920 Well, there's a huge contributing factor you might not know about. 00:00:18.920 --> 00:00:22.840 I'm talking about NAND cell performance. You know. 00:00:22.840 --> 00:00:28.240 NAND is just a specific type of memory used in SSDs that actually holds your data, and 00:00:28.240 --> 00:00:31.560 a cell is the smallest unit of that memory. 00:00:31.560 --> 00:00:36.800 Each cell holds a tiny bit of data, between one and five bits each, meaning you'd need 00:00:36.800 --> 00:00:39.960 several cells just to store a single letter. 00:00:39.960 --> 00:00:44.600 And exactly how many bits a cell can hold has become a crucial differentiator when buying 00:00:44.600 --> 00:00:50.280 an SSD. You see, the more bits a cell can hold, the higher the capacity of the drive at the same 00:00:50.280 --> 00:00:58.160 cost. But there's a trade-off. More bits per cell also means less longevity and less speed. 00:00:58.160 --> 00:01:04.680 In other words, the drive will wear out faster. These things happen because more bits are written over all to each cell, shortening 00:01:04.680 --> 00:01:09.080 their lifespan, and the additional bits means it takes longer for the drive to figure out 00:01:09.080 --> 00:01:13.720 exactly what data needs to read from or be written to each cell. 00:01:13.720 --> 00:01:18.440 This higher data density also means that the error rate can increase. 00:01:18.440 --> 00:01:23.660 This is because temperature fluctuations can cause electron leakage in tightly packed cells, 00:01:23.660 --> 00:01:29.140 so the controller chip of the drive has to perform more error-correcting functions, slowing 00:01:29.140 --> 00:01:34.940 the drive down even more. Come on! 00:01:34.940 --> 00:01:40.620 But, spoiler alert, using more bits per cell is the primary way we're getting bigger, 00:01:40.620 --> 00:01:45.420 cheaper drives. So how the heck are we making up for their speed shortcomings? 00:01:45.420 --> 00:01:49.420 One very common method is caching, which can be done in two ways. 00:01:49.420 --> 00:01:54.860 One by using high-speed DRAM on the SSD, similar to what you'd find in your main system memory. 00:01:54.860 --> 00:02:00.460 Or two, by treating a small portion of the drive as fast, one-bit, single-level cells 00:02:00.460 --> 00:02:06.140 or SLCs by only writing one bit to each cell, even if it can hold more. 00:02:06.140 --> 00:02:13.020 I can do more, coach! Put me in! For operations that can be completed in short bursts, the SSD will make use of one of these 00:02:13.020 --> 00:02:19.820 kinds of cache to keep speeds high. The transfer rates only drop if large amounts of data have to be moved, resulting in the 00:02:19.820 --> 00:02:27.180 cache filling and the drive having to fall back onto slower MLC, TLC, or QLC cells. 00:02:27.180 --> 00:02:31.580 That's short for multi-level, triple-level, and quad-level, respectively, which can hold 00:02:31.580 --> 00:02:39.660 two, three, or four bits a piece. And some lower-end drives even use some of your PC's main memory as cache to leverage 00:02:39.660 --> 00:02:43.660 the benefits of faster memory without adding cost to the drive itself. 00:02:43.660 --> 00:02:48.580 Another strategy is simply to stack NAND cells on top of each other to increase data density 00:02:48.580 --> 00:02:52.620 rather than going to a higher and slower level of cell. 00:02:52.620 --> 00:02:57.380 This has been heavily marketed by Samsung in particular as VNAND technology, where the 00:02:57.380 --> 00:03:01.660 V stands for vertical. As in, sick vert, bro. 00:03:01.660 --> 00:03:06.300 But how far can we go in terms of cramming more bits into one cell while still keeping 00:03:06.300 --> 00:03:13.500 speeds reasonable? Well, it looks like PLC, or Penta-level cell SSDs, are on their way and might appear in 00:03:13.500 --> 00:03:18.980 2025. But as you can probably figure out, each time you add another bit, you see more and more 00:03:18.980 --> 00:03:23.860 of a diminishing return in terms of performance overhead and relative capacity, resulting in 00:03:23.860 --> 00:03:27.980 PLC only giving you a 25% increase in storage. 00:03:27.980 --> 00:03:32.940 And because of the complexity inherent in increasing capacity up to five bits per cell, 00:03:32.940 --> 00:03:38.540 the drives will need new controller chips, hence the delay in getting PLC SSDs to market. 00:03:38.540 --> 00:03:42.740 And once they do arrive, they might not be all that great for folks who need to write 00:03:42.740 --> 00:03:47.420 to them often, such as content creators or gamers who frequently change up the titles 00:03:47.420 --> 00:03:53.900 stored in their local drives. That's the longevity concern we touched on earlier, which, unlike speed, may not be 00:03:53.900 --> 00:03:57.580 figured out by the time PLC drives hit store shelves. 00:03:57.580 --> 00:04:03.580 But still, PLC NAND should be a way to store unprecedented amounts of data cheaply, unless 00:04:03.580 --> 00:04:07.100 you're willing to go back to old-school mechanical hard drives. 00:04:07.100 --> 00:04:20.700 I do kind of miss the little click-clack noises they make.