Samsung is giving 3D V-NAND a little TLC

Samsung's 3D flash memory, known as V-NAND, powers its 850 Pro SSD and looks to be a compelling alternative to traditional flash memory.

V-NAND achieves higher bit densities by stacking multiple cell layers on top of one another. This approach avoids the interference and patterning issues that chipmakers have encountered when shrinking traditional flash memory based on planar technology. In theory, V-NAND should scale to much higher densities than conventional flash.

Multi-level stacking isn't the only weapon in Samsung's arsenal, though. The firm's more conventional triple-level cell (TLC) flash achieves higher densities on a single plane by cramming three bits into each cell, one more than the usual multi-level cell (MLC) config.

Now, we've learned that the TLC technique is being applied to 3D V-NAND.

During the Q&A session of its SSD Global Summit in Seoul, South Korea, Samsung told us that it plans to make an announcement related to three-bit V-NAND. We don't know when that announcement will come or what it will entail—Samsung's SSD department is notoriously stingy with details—but it's worth noting that Samsung's second-gen V-NAND announcement mentioned "higher-density" drives due later this year. Those would be good candidates for TLC V-NAND.

Before the haters start piling on, it's worth noting that V-NAND's benefits should balance TLC's baggage to some extent. TLC gets a lot of flak because storing an extra bit reduces the write speed and endurance of individual flash cells. However, V-NAND's reduced interference enables a simpler programming algorithm that improves write performance. Also, its 3D charge trap cells have higher endurance than planar equivalents based on floating gates. In other words, V-NAND and triple-level cell storage would seem to be nicely complementary technologies.

For consumer SSDs, TLC's drawbacks seem largely inconsequential, even with traditional NAND. The TLC-based Samsung 840 Series in our SSD Endurance Experiment wrote hundreds of terabytes before burning out, which is far more than typical folks need. And its successor, the 840 EVO, already uses a clever SLC cache to offset TLC's slower write speeds. Given everything, then, Samsung should have all the tools it needs to make a compelling consumer drive based on TLC V-NAND.

Comments closed
    • smilingcrow
    • 7 years ago

    After reading this I managed to bag a brand new 1TB version for £230 for my laptop; couldn’t resist at that price. 😉

    • internetsandman
    • 7 years ago

    With this stacking method, along with TLC NAND, I would assume that drive capacities north of 2TB become rather easy to reach. I’m assuming cost will prevent Samsung from venturing into that territory though, I would love to be wrong.

    • Generic
    • 7 years ago

    All of this SLC v. MLC v. TLC discussion leaves me wondering why the drive manufacture doesn’t give the user the option to pick for themselves; similar to the “Allocation unit size” when formatting a drive. Firmware storage space can’t be that precious, can it?

      • f0d
      • 7 years ago

      this is something i always thought would be a great thing to do

      we know it probably can be be done – look at samsung’s 840 evo where part of the flash memory is in SLC mode

      even better would be if we could have all three modes on a single ssd – write caching on SLC, frequently written areas in MLC and storage (stuff that hasnt changed in a while) on TLC

      i know theres all sorts of problems and it most likely wont happen but it would be awesome if it could be done tho

    • Welch
    • 7 years ago

    For anyone not understanding the purpose of a TLC 3D V-Nand, it’s simple. You get performance and reliability of an SSD but closer to hard drive capacities at a semi affordable cost. So who cares if the drive will “only” do 400-500 ish reads and maybe 400 writes, that beats the hell out of any hard drives in a single disk. With the possibility of getting probably 2tb onto a single drive!

    This quickly becomes a great alternative to individuals who need more than 500gb storage, but don’t want the performance of a traditional hard drive. The current endurance of TLC is much tougher than say 90% of consumers needs. Add on top of that the ability to extend it’s lifespan by 2-10 times and you have a recipe for one heck of a storage drive that can easily double as a system drive for those not worried about a 150-200 mb/s write missing from higher priced per GB drives.

    If this is what I think it is… it’s the first step towards truly abandoning hard drives for consumers.

      • cosminmcm
      • 7 years ago

      The purpose of TLC 3D V-Nand seems to be to lower Samsung’s costs, not the final price. The price of the TLC drives should be the lowest, no matter the performance offered. Unfortunately this doesn’t seem to be the case.

        • HisDivineOrder
        • 7 years ago

        Exactly. The purpose of 3D V-NAND was ostensibly to increase the performance and size options for future drives. The purpose of TLC was to reduce costs and meaningfully drop the prices of SSD’s to broaden their appeal to the masses.

        So far, neither radical changes to the size proposition or cost structure have happened. It’s hard to believe then that by combining the technologies we’re going to see these things then magically happen.

          • Spunjji
          • 7 years ago

          I’m willing to give them the benefit of the doubt for one generation on both technologies to recoup R&D. After that it’s just plain gouging.

    • DragonDaddyBear
    • 7 years ago

    The Evo far outlasted what I would consider to be the useful life of a drive, based on my usage. Adding to that, these “3D” chips are, what, 40nm and they are working to stack more layers? I foresee a lot of potential in 3D TLC NAND.

    • MarkG509
    • 7 years ago

    Though I haven’t bought anything yet in this regard, I’m starting to move away from wanting SATA SSDs, and instead looking at PCIe and NGFF SSD “sticks” that fit either on the very latest mobo’s or on PCIe adapter cards. PCIe x4 or x8 adapter cards that take from 1 to 4 sticks can be had for < $20.

    • HisDivineOrder
    • 7 years ago

    The chief complaint I have about TLC is not its reliability by itself, but actually the downsides of TLC are not being offset by a real cost advantage against competition that do not have the same downsides.

    Even somewhat mitigated, I find the value proposition of TLC based on 3D V-NAND to be unlikely to win me over. Why? Because when they brought this same tech to MLC, they cost their drives higher than the equivalent drives by the competition that used the older technology and at sizes less than the promise of 3D V-NAND should have allowed.

    Given that, I highly suspect we’ll see Samsung pocket any advantage that going with the newer process gets them and what we’ll see instead are more drives that push the edge of the performance boundaries of SATA while being overpriced for what they’re offering compared to the competition.

    Except this time with reduced warranties.

      • smilingcrow
      • 7 years ago

      Samsung SSDs seem to have a vaguely Applesque level of consumer appreciation hence there is currently no requirement for them to lower prices.
      So the issue is around their competition and how they compare or more precisely the perception of how they compare.
      I imagine most Samsung SSDs are sold to OEMs anyway so that is where the real money is.

      • DPete27
      • 7 years ago

      You’re exactly right. Samsung is technologically ahead of the competition. And while they’re definitely pushing the SSD market forward, they’re using their popularity to market their cheaper-to-manufacture SSDs as a semi-premium product. While that’s just good business (they make much higher profits than others), it also stings that we the consumers don’t get reduced prices.

      • Farting Bob
      • 7 years ago

      The 840 EVO is TLC and offers pretty much the best performance/£ along with the crucial M550 (which suffers more at sub 500GB sizes). They arent the cheapest drives, but they are generally better than all the cheaper drives.

    • UnfriendlyFire
    • 7 years ago

    “TLC gets a lot of flak because storing an extra bit reduces the write speed and endurance of individual flash cells”

    Crucial MX100s, not the fastest, yet quite popular, and there was a Samsung SSD 850 Pro review that mentioned the MX100 as part of the reason why the 850 Pro wasn’t worth purchasing.

    Why? Because cost per GB.

    As for the write endurance, if you’re using consumer SSDs in a server workload, I hope you got a backup plan for premature SSD failures.

    • MadManOriginal
    • 7 years ago

    I wonder how high-performing SLC V-NAND would be. Maybe Samsung will make some for ultra high-end systems to compete with the likes of FusionIO, although I don’t think it’s too likely because the volumes are probably too small.

      • Pwnstar
      • 7 years ago

      You can tell the controller to treat TLC NAND as SLC.

        • MadManOriginal
        • 7 years ago

        Yes, I know, it doesn’t mean they will release an all-SLC drive.

          • Pwnstar
          • 7 years ago

          I’m saying you can have yourself an all-SLC drive if you are OK with having a drive 1/3 the size of what you bought.

      • faramir
      • 7 years ago

      Why would they be too small ? Samsung just came up with 1 TB 3D MLC drive. One of these configured as SLC would be 512 GB in size and cost exactly the same amount in materials as that 1 TB MLC. 100% markup for enterprise gear over consumer bits ? Nothing unheard of, plus the capacity is very reasonable..

    • BoilerGamer
    • 7 years ago

    Get 850 Evo 1TB under $350 and you can have my money Samsung!!

      • Generic
      • 7 years ago

      I, on the other hand, require 2TB and PCIExpress to part with said $350. Just in case you cared to know, dear friend Samsung. 😉

        • MadManOriginal
        • 7 years ago

        *yawn* wake me up when it’s $25 per PCIExpress lane.

          • Wirko
          • 7 years ago

          Per day for rent?

          • UnfriendlyFire
          • 7 years ago

          A friend told me he would only buy an SSD if it was as cheap as HDDs.

          He still uses his RAID0 7200rpm array, and yet his OS boot time is slower than a crippled Kingston SSD (*cough* bait-and-switch *cough*).

    • wierdo
    • 7 years ago

    Would be curious to see how this all balances out, I’m still not sure how the V-NAND MLC ones compare to traditional ones, Samsung claims it’s higher endurance (2x ~ 10x supposedly) and for now I’ll give them the benefit of a doubt.

    If TLC drops endurance by a third vs MLC in this case as well then I figure it should still be somewhat comparable to non V-NAND MLCs right?

    Might be a decent compromise, who knows. Hopefully the future endurance bench will find out.

      • robliz2Q
      • 7 years ago

      It seems strange marketing, it muddies the nice clean story V-NAND with the TLC again, which they already rebranded as MLC on some recent drives, so they must know it’s a tradeoff many would rather avoid.

        • MadManOriginal
        • 7 years ago

        Rebranded as MLC?

      • faramir
      • 7 years ago

      “If TLC drops endurance by a third vs MLC in this case as well then I figure it should still be somewhat comparable to non V-NAND MLCs right?”

      It doesn’t work like this. In a purely theoretical model (statistics … [*]), moving to higher bit density per cell drops the endurance by a factor of 2, while increasing the amount of data by 1 (bit). To illustrate:

      Going from SLC (1 bit/cell) to MLC (2 bits/cell) you get half the endurance of SLC at twice the capacity.

      However going from MLC to TLC (3 bits/cell) you get 1/4 the endurance of SLC at three times its capacity – diminishing returns. You always lose 1/2 compared to the level above it (one half when going from MLC to TLC).

      If there was a four bits/cell technology out there (let’s call it QLC), it would offer only 1/8th of endurance of SLC with 4 times the capacity of SLC.

      [*]: Note that real world scaling is even worse than this and moving to higher bit density per cell incurs additional endurance penalty (on top of what one would expect from purely theoretical model)..

        • f0d
        • 7 years ago

        yet looking at the TR endurance test the TLC drive lasted much longer than 1/2 the endurance of MLC

        so i dont think its as simple as 1/2 1/4 1/8

        • wierdo
        • 7 years ago

        Hmm, my understanding was – and these numbers are vaguely accurate, I don’t know which process is used etc:

        SLC ~100k writes
        MLC ~3-10k writes (varies depending on process etc)
        TLC ~1-3k writes (varies depending on process etc)

        So I wouldn’t say the drop in endurance corralates linearly with number of bits. I don’t know how V-NAND factors into this either, I have no idea, but for now I’m going with the assumption it’s a similar slope until numbers come out and someone tests it.

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