1 00:00:00,000 --> 00:00:04,480 Eight terabytes of solid state storage for less than 500 bucks? 2 00:00:04,480 --> 00:00:09,160 Back in 2009, you would have paid that much for a mere 32 gigs of space. 3 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? 4 00:00:15,480 --> 00:00:18,920 Well, there's a huge contributing factor you might not know about. 5 00:00:18,920 --> 00:00:22,840 I'm talking about NAND cell performance. You know. 6 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 7 00:00:28,240 --> 00:00:31,560 a cell is the smallest unit of that memory. 8 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 9 00:00:36,800 --> 00:00:39,960 several cells just to store a single letter. 10 00:00:39,960 --> 00:00:44,600 And exactly how many bits a cell can hold has become a crucial differentiator when buying 11 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 12 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. 13 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 14 00:01:04,680 --> 00:01:09,080 their lifespan, and the additional bits means it takes longer for the drive to figure out 15 00:01:09,080 --> 00:01:13,720 exactly what data needs to read from or be written to each cell. 16 00:01:13,720 --> 00:01:18,440 This higher data density also means that the error rate can increase. 17 00:01:18,440 --> 00:01:23,660 This is because temperature fluctuations can cause electron leakage in tightly packed cells, 18 00:01:23,660 --> 00:01:29,140 so the controller chip of the drive has to perform more error-correcting functions, slowing 19 00:01:29,140 --> 00:01:34,940 the drive down even more. Come on! 20 00:01:34,940 --> 00:01:40,620 But, spoiler alert, using more bits per cell is the primary way we're getting bigger, 21 00:01:40,620 --> 00:01:45,420 cheaper drives. So how the heck are we making up for their speed shortcomings? 22 00:01:45,420 --> 00:01:49,420 One very common method is caching, which can be done in two ways. 23 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. 24 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 25 00:02:00,460 --> 00:02:06,140 or SLCs by only writing one bit to each cell, even if it can hold more. 26 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 27 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 28 00:02:19,820 --> 00:02:27,180 cache filling and the drive having to fall back onto slower MLC, TLC, or QLC cells. 29 00:02:27,180 --> 00:02:31,580 That's short for multi-level, triple-level, and quad-level, respectively, which can hold 30 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 31 00:02:39,660 --> 00:02:43,660 the benefits of faster memory without adding cost to the drive itself. 32 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 33 00:02:48,580 --> 00:02:52,620 rather than going to a higher and slower level of cell. 34 00:02:52,620 --> 00:02:57,380 This has been heavily marketed by Samsung in particular as VNAND technology, where the 35 00:02:57,380 --> 00:03:01,660 V stands for vertical. As in, sick vert, bro. 36 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 37 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 38 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 39 00:03:18,980 --> 00:03:23,860 of a diminishing return in terms of performance overhead and relative capacity, resulting in 40 00:03:23,860 --> 00:03:27,980 PLC only giving you a 25% increase in storage. 41 00:03:27,980 --> 00:03:32,940 And because of the complexity inherent in increasing capacity up to five bits per cell, 42 00:03:32,940 --> 00:03:38,540 the drives will need new controller chips, hence the delay in getting PLC SSDs to market. 43 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 44 00:03:42,740 --> 00:03:47,420 to them often, such as content creators or gamers who frequently change up the titles 45 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 46 00:03:53,900 --> 00:03:57,580 figured out by the time PLC drives hit store shelves. 47 00:03:57,580 --> 00:04:03,580 But still, PLC NAND should be a way to store unprecedented amounts of data cheaply, unless 48 00:04:03,580 --> 00:04:07,100 you're willing to go back to old-school mechanical hard drives. 49 00:04:07,100 --> 00:04:20,700 I do kind of miss the little click-clack noises they make.