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Ask HN: Why are flash memory prices going down so much faster than RAM?

by altoz on 1/2/17, 3:58 AM with 76 comments

• by keenerd on 1/2/17, 4:51 AM

  The obvious answer: flash can hold multiple bits per cell and ram can't.

  MLC is half as expensive as SLC. TLC is 33% less expensive than MLC. QLC is 25% less expensive than TLC and 75% cheaper than SLC. Not to mention transparent compression algos. As the controllers improve you can get more bits of storage from the same amount of flash for free. Longevity and reliability suffers, but hey, cheap SSDs!

  Ram only gets cheaper by improvements to semiconductor processes, which also can be applied to make flash cheaper. (Big fat asterisk, those processes are very different.) While improvements to flash that allow more levels per cell can't be applied to ram. The price difference between flash and ram will only continue to grow.

  Modern flash is quite "analog". The first company to figure out how to reliably store 32 voltage levels per cell (Five bits. PLC?) will make a quick billion.

• by astrodust on 1/2/17, 7:08 AM

  DRAM type memory uses a completely different process than flash even if they're both a form of "memory". The performance of DDR-type memory is well beyond anything in the Flash world.

  Today 2GB/s is considered very good for an SSD but that would be brutally slow for system memory. DDR4 memory is typically 30-60GB/s per bank with the low end being two-channel, the high end being four.

  DRAM has also been the subject of aggressive research and development for many, many decades while large-scale production of flash is a relatively recent phenomenon. It's the widespread adoption of smart phones, thinner notebooks, and ubiquitous USB keychain type devices that as pushed it to the volumes it's at now.

  There's also the concern that DDR memory must have a very high level of data integrity, bit-flip errors are severely problematic, and it can't wear out even after trillions of cycles. Flash has more pervasive error correction, and while wear is a minor concern, it's still possible to exhaust it if you really, really try.

  I'd say the reason flash memory prices are steeply down is the new "3D" process used by Intel and Samsung has been a big game-changer, allowing for much higher density. DRAM has seen more gradual evolution through the last few generations.

• by paws on 1/2/17, 4:33 AM

  For some historical context this is worth remembering:

  https://en.wikipedia.org/wiki/DRAM_price_fixing

• by xenadu02 on 1/2/17, 5:19 PM

  It is not the speed, reliability, or processes.

  There are numerous flash manufacturers all racing each other to build out capacity and increase density because they want to eat the HDD market.

  DRAM is controlled by a small cabal, all of whom have multiple convictions for price fixing and collusion. I believe Hynix shipped some sacrificial C-suite execs to do prison time in the US over it. To a large degree no one is building out DRAM fab capacity as well.

  DRAM prices have stayed high because the manufacturers want it to stay high and are colluding (either explicitly or implicitly) to keep prices up. The capital cost to compete is enormous: many billions before you can make your first sale. The day you break ground memory prices will mysteriously drop so low as to make your venture unprofitable, meaning your commercial loans get called in and you go bankrupt. Everyone understands this and avoids attempting to compete.

• by zeta0134 on 1/2/17, 4:29 AM

  If I had to wager an uneducated guess, I would propose that the recent mainstream acceptance of Solid State Drives as a viable, affordable alternative to spinning disk drives, has created a sudden demand in Flash memory that's caused that industry to thrive.

  At least at the retail level in the Best Buy where I worked until recently, I watched Solid State drives transition from something only high end computers had to something that was standard even among the lower priced value machines. We had customers complaining about the smaller drive sizes because they were so accustomed to the gigantic storage offered by the spinning disk media at its height in popularity.

  I'd love someone with more industry knowledge to chime in though, as my own experience here is pretty limited. This is simply what I've observed in my own corner of the world.

• by slededit on 1/2/17, 5:07 AM

  RAM is only capable of storing one bit per cell. FLASH didn't really take off until MLC technology came around giving the ability to store multiple bits per cell which vastly increased the density.

  Theoretically RAM could be built that way but it would be much slower. Every cell read/write would need to go through an ADC/DAC, and the noise is much higher due to leakage. This slowness isn't much of a problem for FLASH because its competition was spinning disks that were slow as molasses anyways.

• by candiodari on 1/2/17, 4:40 AM

  I think this works by providing a second application for older chip manufacturing facilities. For SD chip designs, speed and size effectively do not matter (the controller will matter a hell of a lot more for final speed than actual storage chips speed). So they're using the chip fabs that everyone else is abandoning.

  As a second bonus, even on old systems SD card circuits are relatively small (compared to a 5-60" LCD they certainly are). Wafers are round and old wafers are used to manufacture LCD displays, so small chips can be placed around them in the manufacturing process and get really good economics by having lots of manufacturing options.

  So same reasons displays are getting cheap, except they're even better. So the race to the bottom is happening pretty fast for SD cards.

  Not entirely sure about this. Might be entirely wrong, but I'm not sure how to confirm this.

• by CoolGuySteve on 1/2/17, 9:00 AM

  Slow SSDs have gone down in price, but fast SSDs are still expensive. For example, you can get a 500GB Samsung 850 for about $130 but a Samsung 960 evo costs $250, and then another $100 on top of that for the 960 pro. Those 3 drives range from 600MB/sec to 2222MB/sec linear reads, the fastest costing the same as a 600MB/sec SSD did 3 years ago.

  The demand for slow RAM drops precipitously after the whatever Intel chipsets use it stop being used in new systems (not sure if the same is true in the embedded market). For example, nobody's buying DDR2 these days. So the economies of scale dissipate and fabs retool faster.

  So while both devices have economies of scale, SSDs have an extra dimension to their demand curve for performance that allows for slower higher density chips to still be profitable.

• by haberman on 1/2/17, 6:14 AM

  A question that seems related: what the heck is up with memristors? The Wikipedia page (https://en.wikipedia.org/wiki/Memristor) says that memristors are estimated for commercial viability in 2018, and have been built in prototype, but also says that there are serious doubts about whether memristors can possibly exist in physical reality! What gives?

• by ksec on 1/2/17, 5:40 AM

  1. There little demand for more memory. 2. There are only a few Memory makers left on the market. 3. Moore's Law no longer applicable, smaller transistor isn't necessarily cheaper any more. 4. You can have a Bad NAND, you dont want a Bad memory.

  China has decided to pour in 10s of Billions into the NAND and DRAM industry by 2020, until then the price should very much stable / predictable.

• by markhahn on 1/2/17, 5:02 PM

  Why does the OP imply that there is some relation between the two products? It's true that both use litho and si, but they are dramatically different, internally.

  Think of flash as a consumable media - it is, since each cell can only be erased a few hundred times. After all, that's what it means when the vendor says "200TBW for 256G device": you can expect 7-800 cycles per cell. This is also why vendors are pushing capacity so hard: it lets them push down the price while at the same time not needing to improve endurance.

  So in some sense, the answer is "endurance", since the physics of flash erasure necessitate high capacity, and no one would buy the extra capacity unless it were also relatively cheaper. Whereas DRAM doesn't wear out...

• by static_noise on 1/2/17, 8:41 AM

  After reading through the answers here, I don't think the real answer has been given.

  Is it the technology?

  * Flash cells can store more data an be produced cheaper per cell. But they are more complex to read out and slower.

  This can explain some factor, but the factor of 40 given by OP probably not.

  * Flash and DRAM probably use different processes.

  This could explain a bit but look at the next point...

  * DRAM has a much longer history and (at least in the beginning) much higher capital investment.

  ...which means that DRAM should have the technological advantage. At least through economies of scale.

  Is the cumulative investment in flash research already much bigger compared to DRAM research?

  Is the process used to produce flash memory so much easier?

  Is it the market?

  * Obviously people pay the price.

  * With DRAM people are hungry for performance more than they are for size.

  * We already have more than enough DRAM. The latest MacBookPro demonstrates that 16 GB DRAM is enough for just about everybody but flash storage goes up to 1 TB.

  * Of those 16 GB DRAM the speed and power consumption are much more important than the raw size.

  Coming back to the cumulative investment. I think that the primary pain point for flash has been the price per GB. Flash could be stronger, faster, more reliable, less power consuming but those are all secondary. It is fast and reliable enough by using very complex RAID controllers. The power consumption is not as bad as HDDs already use a lot and the data mostly just sits around. The main driving point is the price per GB. This is where the money goes in flash development.

  On the other hand for DRAM, after some point, it is mostly speed and power driven. Reliability has to be comparatively high as every cell must work over years. Size is mostly increased by improving semiconductor processes where flash probably uses a lot of the same technology. Using the layer stacking technologies of flash is probably not yet applicable because it is not reliable enough and not compatible with the cell layout, maybe it never will.

  If we really were hungry for so much RAM we would probably get it. But we aren't. It's good enough. Progress slows down.

• by nickpsecurity on 1/2/17, 4:46 AM

  Looking at Hynix's financials, they're making enough money to reduce the cost of RAM quite a bit. Looks like it's just them maximizing their profit as one would expect. I assume it's similar for the rest. As always with for-profit firms selling hardware or I.P..

• by kabdib on 1/2/17, 4:57 PM

  An additional point: People don't know the quality of the flash they are buying. You're seeing bottom-bin crappy parts made to look better than they are with ECC. You're also NOT seeing data retention; that cheap USB stick may develop unreadable blocks sooner (this is much more likely with TLC and QLC, where the difference between two bit values can be measured in the hundreds or even dozens of trapped electrons).

• by deathhand on 1/2/17, 4:38 AM

  RAM is written to faster than any other component other than the onboard processor cache.

• by smitherfield on 1/2/17, 7:39 AM

  Read/write speeds for DRAM are much faster than flash (although the gap is closing and the day may soon come where computers are sold with flash storage but no DRAM, and the distinction between memory and storage is done away with).

  DRAM is also a much more mature technology than flash is, so more of the low-hanging fruit for improvement has already been taken advantage of.

• by eschutte2 on 1/2/17, 4:29 AM

  RAM is more expensive to produce in general (more transistors, more stringent specs as you mentioned), but as to rate of change, that seems more likely to be due to competitive pressures and maybe more rapidly increasing demand for flash in recent years versus RAM.

• by tjpaudio on 1/2/17, 4:41 PM

  All technical reasons aside, it has got to be mostly demand. I can't see computers coming pre-configured with more than 64gb, but for storage there is increasingly more demand as the price reaches parity with spinning disks. One thing that is true is we are as storage-hungry as ever. High res photos created by every phone, companies logging every minute process in hopes of using it for analysis later... Our need for storage vastly outstrips our need for RAM.

• by ryao on 1/2/17, 4:56 PM

  The market for DRAM is relatively mature while the market for flash is still developing as it canabalizes the hard drive market. Consequently, you see flash taking advantage of newer processes and techniques first as flash manufacturers aim for ever greater volumes in pursuit of profits.

• by yuhong on 1/2/17, 4:43 AM

  I think NAND flash is more flexible in terms of design than DRAM is, for example 3D NAND. NAND flash generally communicate through a separate controller that uses for example the SATA or USB buses, while the DRAM controller is built into the CPU or chipset.

• by bitJericho on 1/2/17, 5:32 PM

  And here I am with 24gb ecc ram for 40 bucks on eBay. Workstation PCs ftw!

• by sushirain on 1/3/17, 8:16 AM

  This is the relevant chart:

  http://www.jcmit.com/mem2015.htm

  DIMM seems to go down slower lately.