Intel and Micron Put Their Shared Past Behind Them...

In 2018, Intel and Micron decided to end their long-running memory partnership, going their separate ways first for NAND flash development after their 96-layer node, and then for 3D XPoint memory after completing development of its second generation. The split was completed in 2019, and in 2020 we saw the first post-divorce developments from both players. Intel has introduced 144-layer 3D NAND as their follow-up to the 96L generation, with a variety of consumer and enterprise SSDs announced earlier this month.

Micron used the breakup as the opportunity to make more significant changes, switching their 3D NAND design from a floating gate memory cell to a charge trap cell design with a replacement gate manufacturing process, much more similar to what everyone other than Intel has been doing since the transition from planar to 3D NAND. Micron initially made this switch with a 128L generation that was used as a low-volume trial, and quickly followed up with their recent announcement of a 176L generation. That has ostensibly already started shipping in some products, but Micron won't identify them and their 176L NAND won't really begin to have an impact on the SSD market until well into 2021.

... And Intel Makes a New Deal

After ending the Micron partnership, Intel's NAND and SSD business was the odd man out in the industry. They're the only player focused on 3D floating gate designs, and their product line is very strongly focused on the enterprise/datacenter SSD market, with consumer SSDs as more of an afterthought. They are also putting far more of an emphasis on QLC NAND than any other player in the SSD market: in May, they even confirmed that they would not be releasing any more consumer SSDs with TLC NAND. Some of this QLC focus is an attempt to promote their 3D XPoint-based Optane products for fast tier storage, but the fact remains that Intel's newly independent 3D NAND business is relatively small and specialized within the NAND industry.

Given its new station in the market, it isn't too surprising that Intel's NAND business became the next acquisition target. In October, SK hynix and Intel announced a deal for SK hynix to purchase Intel's 3D NAND business and their NAND-based SSD product lines, leaving Intel with their Optane products as their only storage offerings. This acquisition will be an unusually long, drawn-out process with the final part of the transfer planned for March 2025. Once the deal gets regulatory approval (expected sometime in 2021, probably later in the year), SK hynix will get ownership of Intel's NAND fab and the SSD business and IP (eg. Intel's NVMe SSD controller designs). Meanwhile, Intel will retain their 3D NAND IP and the employees operating their NAND fab. The NAND IP and fab employees will be transferred at the end of the process, in 2025.

Neither company has commented on how this acquisition will affect their long-term technology roadmaps, but it's easy to imagine that by 2025 Intel's 3D floating gate may be a dead-end and SK hynix would switch the Intel fab in Dalian, China over to whatever charge trap based process the rest of the SK hynix NAND fabs are using at the time. Even though the differing 3D NAND technologies may not be practical to maintain in the long run, in the short term the SK hynix and Intel SSD businesses are quite complementary. They're two of the smaller players in the NAND market, but with relatively little overlap. SK hynix sells twice as many SSDs as Intel but lower total capacity in GB, so clearly SK hynix will be acquiring a much larger presence in the high-capacity enterprise SSD market—which is also the most profitable market segment. Meanwhile, SK hynix has recently become much more competitive for consumer SSDs after their first several generations of 3D NAND made them a perennial also-ran in the SSD market and left their 3D NAND mostly relegated to mobile (smartphone) storage and memory cards. The combined SK hynix + Intel NAND business is on track to have the second-largest market share in the NAND market.

Related Reading: SK Hynix to Buy Intel’s NAND Memory Business For $9 Billion

More Layers And Faster Interfaces

As the major flash memory manufacturers roll out new generations of 3D NAND flash memory, we have seen some of both diversification and convergence of the technologies implemented by the various manufacturers. The layer counts for 3D NAND are starting to get a bit confusing: At the 96-layer node, Samsung stuck out with just 92 layers—they came up a bit short because they managed to avoid using string stacking in their manufacturing process. Beyond 96 layers, the roadmaps for layer count are all over the place. Kioxia and Western Digital announced 112L NAND at the beginning of 2020, but we haven't seen it hit the market yet. Intel jumped from 96L to 144L. Micron made a short stop at 128L before continuing on to 176L. SK hynix started shipping 128L and has also recently announced 176L. Samsung's 128L debuted with the 980 PRO. It takes months to over a year to get from a NAND manufacturer announcing a new node to sampling that NAND to ramping up production enough for it to appear in mass-market consumer products, so most of the consumer SSDs on the market today are still 96L models with some of the newer drives using 128L NAND. In 2021 we should see someone announce 200+ layer 3D NAND, but new products hitting the shelves will feature anywhere from 112 to 176 layers.

The layer count for 3D NAND is a decent indicator of each generation's density cost per GB, but another metric is becoming important: IO performance per die. The speed of IO between the NAND flash and the SSD controller can be a limiting factor for the drive's overall performance. For a PCIe 3.0 x4 SSD with an 8-channel controller, running each channel at 533MT/s with TLC NAND was sufficient to provide the ~3.5GB/s sequential read performance that saturates the PCIe link. Now that drives are moving to PCIe 4.0, both NAND and SSDs need to support higher IO speeds. There's also a trend toward using four-channel controllers for mainstream consumer SSDs and reserving 8-channel controllers for high-end consumer and entry-level datacenter drives, and this is also driving a need for higher IO speeds. We're now seeing most PCIe 4.0 SSD controllers supporting 1.2GT/s to 1.6GT/s IO speeds, with the latest NAND generations offering similar speeds. This big jump in per-die performance is how the SK hynix Gold P31 with a 4-channel controller was able to match the performance of other PCIe 3.0 SSDs with 8-channel controllers, while using far less power. NAND IO speeds will probably stall again for a generation or two after PCIe 4.0 goes mainstream, until PCIe 5.0 or later starts to catch on in the storage market.

Related Reading:

3D XPoint and SLC NAND Remain Niche Technologies

At the very high end of the SSD market and almost exclusively for top of the line enterprise SSDs, there are memory technology options aside from the QLC and TLC NAND used in mainstream SSDs. 3D XPoint memory is an alternative to NAND flash memory, and was developed by Intel and Micron. Micron has technically commercialized 3D XPoint with their limited-release X100 SSD, but otherwise Intel's Optane products are almost synonymous with 3D XPoint memory. Intel's first product to use second-generation 3D XPoint memory was formally announced earlier this month: the Optane SSD DC P5800X, replacing the first-generation P4800X. Intel has actually been sampling this for months, and they have let some independent performance numbers slip out that back up their impressive performance claims—but we still don't have a good idea when to expect widespread availability, or what pricing is like. Intel's other Optane products are still using the first-gen 3D XPoint memory, including the second generation of Optane DC Persistent Memory DIMMs that are usable with Cascade Lake and Ice Lake Xeons.

After Intel launched 3D XPoint memory, Samsung responded by bringing back SLC NAND flash memory in the form of their Z-NAND, a latency-optimized 48L 3D SLC NAND. We haven't heard anything new on that front since the 983 ZET two years ago, but Toshiba (now Kioxia) eventually announced their own low-latency 3D SLC memory: XL-FLASH. That memory started sampling this year and is starting to find its way into niche high-end enterprise SSDs from several brands. We have a sample of the DapuStor Haishen3-XL H3900 on our enterprise testbed.

These high-end memories may sound like they offer exciting possibilities for high-end storage, but their impact on the market has been limited and very little has changed in the past year. Everyone is finding 3D TLC NAND to be fast enough for almost every purpose, and the niche for faster-than-TLC storage options will remain tiny. There are no revolutionary new memory technologies poised to shake up the market in the near future.

Related Reading:

NVMe 2.0: Coming Soon, And Already Partly Here

Work has been underway for over a year on version 2.0 of the NVMe specification, but despite the major version number bump it won't be bringing much revolutionary new technology. Instead, the spec is being reorganized to split it into more digestible components with separate documents for PCIe transports and NVMe over Fabrics transports, and different documents for each command set. The NVMe Working Group has been trying to ratify and publish new features without waiting to bundle them all up in the big spec releases, so we already have specs for two new command sets aside from the familiar hard drive-like block storage command set: Zoned Namespaces (ZNS) and Key-Value Namespaces. We covered the ZNS spec in depth earlier this year. It represents a significant change in the abstraction layer between flash memory and application software and allows software to structure its IO patterns in a much more flash-friendly manner, enabling better endurance and performance and lower hardware costs. The SSD industry has been exploring options along these lines for quite a while, including with several proposals for Open-Channel SSDs. With the ZNS spec, it looks like they have finally settled on the right balance for exposing the underlying hardware details without requiring too much software complexity, and lots of companies in the enterprise storage space are on board. Western Digital was the first to announce a ZNS SSD as a commercial product with their Ultrastar DC ZN540.

The other new command set—for Key-Value SSDs—is a subject we haven't covered in as much detail. Conceptually, it's pretty simple: instead of providing the traditional block storage interface with 512-byte or 4kB sectors, the SSD allows reading variable-length values identified by keys rather than logical block addresses (LBAs). This adds only a tiny bit more complexity to the Flash Translation Layer of a typical enterprise SSD, but allows it to offload almost all of the functionality of a key-value database store like RocksDB. As with ZNS SSDs, KV SSDs require significant changes to host software, but in turn offer benefits to performance and endurance. The KV SSD concept doesn't seem to be getting as much interest across the industry, but having it standardized opens the door to wider adoption.

Both of these major new NVMe features are at least initially going to be almost exclusively used by the major hyperscale cloud computing companies, because of the scope of software modifications required. As the necessary modifications roll out to common server application software, these storage features may catch on more broadly in the server market, but there's no easy path for them to make their way into the consumer storage market.

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AnandTech Year In Review 2020: Solid State Drives
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  • Silver5urfer - Wednesday, December 30, 2020 - link

    I'd take an MLC SATA SSD over the overpriced, overheating QLC NVME any day.

    Plus bonus I get MLC SATA, Samsung 860PRO. The last best MLC drive, the NVMe TLC & QLC is only option going forward since Samsung abandoned the MLC with 980PRO. Just look a the TBW of these 860 PROs vs the TLC and QLC Is worst garbage.

    8TB SSD is useless esp when I want to write a lot of data and have them near 80% full, mechanical WD RED / Seagate Exos are much much much better and cheaper options. For those with mATX and other Console type builds they have to adjust to this QLC trash only. EATX and Standard can get any number of SATA drives. Esp all the premium boards have SATA x8 connections. SATA will always be better, newer is never always good. So much of sacrifice and that SLC cache bs and ton of crap.

    Unfortunately for laptops SATA Is almost done, thin and light BGA garbage sells more and Apple made people crave for that thin and light bs so Soldered SSDs and if the OEM cares about user a bit NVMe slots will exist. Even the Clevo machines are now done with SATA I guess.. a shame.

    About consoles, they max around a 2070S and with unified memory arch, do they even have any inherent advantage over ? So far nothing. Load times are one of the benefits but once true next gen games hit, like UE5, Rockstar RAGE and other then we will see how Consoles handle. PC will handle always no matter what, since even in 2020 we are seeing non SSE fixes for the game exes to run the new games. But on the storage side, I do not expect any FPS improvements from SATA to NVMe to Gen 4 SSDs, maybe new Engines will change that ?
    Reply
  • lmcd - Wednesday, December 30, 2020 - link

    Dell XPS 15 7591 shipped with an open 2.5in drive slot, which is part of why I recommended it to my partner. Still thin, around 4lbs.

    2.5in drives were always limited in the 13 inch laptop space. There were already designs that shipped mSATA only. The change is how many people buy 13 inch compared to 14 and 15, and how many 15 inch designs use a different platform than the 13 inch design (leaving 14 as a stretched 13, which stinks).
    Reply
  • Tomatotech - Thursday, December 31, 2020 - link

    “ For those with mATX and other Console type builds they have to adjust to this QLC trash only.”

    Eh? I was putting 5 drives in my mITX builds a couple of years ago, and mITX is far smaller than mATX.

    I used the Fractal Design Node 202 which is one of the smallest mass market mITX chassis at 10 litres. 1x nvme, 3x 2.5” multi-TB HDDs, and another 2.5” SATA SDD. All went in fine, plenty of room, plus a full size 1060 GPU if desired.
    Reply
  • MetaCube - Thursday, December 31, 2020 - link

    NVMe overpriced bad, SATA good Reply
  • mochabean - Wednesday, December 30, 2020 - link

    "there aren't many PCs left that need a SATA SSD for an aftermarket upgrade"

    huh? nvme m.2 slots weren't widespread on desktop motherboards until about 2017 or so. this is just flat out wrong, unless people are chucking their computers in the garbage after 3 years
    Reply
  • Billy Tallis - Wednesday, December 30, 2020 - link

    You are mistakenly presuming that the entire installed base of desktop PCs are in need of some kind of storage upgrade, or will be in the future. This is absurd. Most PCs out there already have adequate storage to finish out the useful lifespan of the system. Of the PC users whose usage will outgrow whatever SSD storage their machine already has, most can either get a hard drive for all their cold data, or they're the kind of power user who isn't running a system so old and low-end that it doesn't have any M.2 or PCIe slots to spare. Reply
  • lmcd - Wednesday, December 30, 2020 - link

    You're mistaken how "power users" actually buy and use systems. Hardware enthusiasts might well fit into your description of power users but it certainly doesn't describe the majority of power users. There are very few power users with unlimited money, and by contrast there are plenty of power users with older systems around that are in use and need storage upgrades at various points. Reply
  • Billy Tallis - Wednesday, December 30, 2020 - link

    "Hardware enthusiasts" and "power users" don't overlap completely, but collectively they're still not capable of driving enough sales through aftermarket upgrades to keep SATA SSDs relevant as more than a niche curiosity in a world where the vast majority of client/consumer systems will never have more than two drives and the first one is NVMe by default because the price premium is so small. Two of the six NAND manufacturers are already done with SATA. And if you think that U.2 will ever catch on for consumer storage, your views on the market are obviously very different from how the manufacturers see it based on real sales data. Reply
  • lmcd - Thursday, December 31, 2020 - link

    There is demand for a storage protocol that delivers high speeds and does not take extensive motherboard space. Reply
  • name99 - Thursday, December 31, 2020 - link

    You're mistaking "power users" with "most of the installed base"... Reply

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