Adata’s SU750 SSD serves up TLC, hold the DRAM

If you've shopped for SSDs recently, you're probably aware of the Adata Ultimate SU800. It's a capable SATA SSD that's been available lately for killer prices. Adata must reckon folks will be happy to find even lower SSD prices, though, because now the company is releasing an SSD to slot directly underneath the SU800. Appropriately, it's called the Ultimate SU750.

This is an educated guess, but as far as we can tell the SU750 is essentially the same SSD as the SU800, just without the DRAM cache. It's still based on 3D TLC flash memory from an unspecified vendor, though—no QLC memory here. Curiously, Adata talks up these drives' durability in its product page blurb yet gives no durability specification beyond a uselessly vague MTBF value of two million hours.

The SU750 supports an SLC-mode caching scheme for improved performance when the drive has free space, but it obviously doesn't make up the difference between it and the SU800. Adata says the SU750 should be good for 65K IOPS on random read operations and 75K IOPS in random writes. We'd expect those numbers to fall pretty sharply when the drive fills up.

Still, as Adata itself points out, it's always going to be a whole lot faster than a hard drive. Drives like this have really made some inroads to crashing the SSD price plane with no survivors. The expected prices that Adata gives—$60 for 256GB, $80 for 512GB, and $150 for 1TB—don't set our hearts alight, but the SU800 is currently selling way below its listed prices. We'll be curious to see what these drives end up costing when they find their way to e-tail.

Comments closed
    • DavidC1
    • 6 months ago

    I got one of the versions of the Silicon Power S55 SSD.

    I could feel the difference in simple browsing with TRIM just after a week of use. Sure the read speed is rated twice as fast and write speed 7x my X25-M drive, but the worst case scenario is worse on the S55. Yea sure the X25-M drive was a super premium drive but it was 9 years ago.

    You need the DRAM buffer. SLC is faster at cell level than 2, 3-bit level MLC but still suffers from the same fundamental problems NAND does.

    • ronch
    • 6 months ago

    $80 for the 512GB? Got my WD Blue M.2 SATA 500MB for $86, no discounts, outside the land of opportunity. $6 saved. Yeah maybe you can buy a burger with that and regret not getting a proper SSD for the rest of your (SSD’s) life.

    • Alexko
    • 6 months ago

    [quote<]Still, as Adata itself points out, it's always going to be a whole lot faster than a hard drive.[/quote<] Is it, though? If your workload makes heavy use of the cache, and doesn't hit the drive proper much, then I suspect there might be cases where a hard drive with a big DRAM cache might be faster than this. Even if such cases were so rare as to essentially never happen, removing the DRAM cache so save a few pennies is stupid and I'm willing to bet this is going to be a terrible product. DRAM caches also help with durability, so that's another issue. Bad, bad Adata!

    • Chrispy_
    • 6 months ago

    Every review of an SSD without DRAM cache that I have ever read reinforces the same, tired old conclusion.

    [b<]DON'T RUIN $100 of NAND by saving $2 on DRAM.[/b<] Review not needed; This [i<]will[/i<] be junk to be avoided at all costs and similarly-priced models will outperform it by huge margins without fail.

      • DancinJack
      • 6 months ago

      ^this

      • ranranran
      • 6 months ago

      ^^+3

      • Usacomp2k3
      • 6 months ago

      They suffer in synthetics, sure, but in real-world usage for light to medium duty, I seem to recall them working just fine.

        • DancinJack
        • 6 months ago

        [url<]https://techreport.com/r.x/2017_10_9_TR200/performance.png[/url<] [url<]https://techreport.com/review/32665/toshiba-tr200-480gb-ssd-reviewed/7[/url<] Yeah, I don't think that's true. Though obviously that depends upon your definition of "fine." My opinion is that there are too many other drives in the price range that do have DRAM cache, and perform significantly better. It's just not worth it to buy these things.

          • Waco
          • 6 months ago

          Those are heavily influenced by write workloads. Consumers, in general, don’t care about write workloads.

          For 99% of people that need an SSD, if there’s a cost advantage to be had, the DRAM-less drives serve the purpose well.

          Without a price advantage, sure, why go with a slower drive?

          EDIT: To further my point – for game loading times (surely we can all relate) these would be essentially identical to SLC, MLC, QLC, etc drives for game storage. I relish the idea of a few terabytes of QLC “crap” SSDs for game storage. Write once, read a bajillion times.

            • DancinJack
            • 6 months ago

            Yeah, I don’t disagree with any of that, but it all comes down to the price thing. These just make no sense unless they’re quite significantly cheaper IMO.

            • Waco
            • 6 months ago

            Agreed. DRAM-less controllers tend to be cheaper too, but the actual sale price is what matters.

            • Takeshi7
            • 6 months ago

            Normal consumers don’t care about write workloads until Windows/Game/Application updates happen. Then it’s freaking brutal. That’s what made me take my Crucial BX200 out of my computer. It was fine for loading things, but as soon as applications or anything needed large updates, it choked bad. And that drive even has DRAM.

            Now I just use it as a glorified thumb drive.

            • f0d
            • 6 months ago

            You must have mad internet to be able to download the updates faster than a subpar SSD can write them

            • Takeshi7
            • 6 months ago

            Installing the updates took longer than downloading them.

            • f0d
            • 6 months ago

            i guess
            but most programs and games i have update at the same time as downloading them, its been a long time since i have actually had to download an update then apply after downloading

          • f0d
          • 6 months ago

          windows and game load times look ok to me
          and as far as i can tell thats what most people care about

        • Chrispy_
        • 6 months ago

        They do work just fine, in the same way that a mechanical disk works just fine.

        The point is not that these drives are terrible, but that they do not equal the performance of similarly-priced drives. Usually the economies of scale of big vertically-stacked manufacturers like Micron/Samsung dwarf the pitiful cost savings of a single DDR3 256 chip.

        Look at it this way; You (as an end user who is also paying a lot of overhead on the DRAM module costs for a PCB, assembly, packaging, distribution, sales, support and retail markup) can obtain a 4GB DIMM with 16x 256GB DRAM packages on it for $16. That puts an upper ceiling on the value of the missing DRAM chip at $1.

        No, ADATA are not spending anything like $1 on the DRAM for their SU800, it’s probably closer to 40 cents – and that’s why the street prices of SSDs without DRAM end up no different to the street price of SSDs [i<]with[/i<] DRAM. Yes, a DRAM-less SSD will [i<]work[/i<] but check out [url=https://techreport.com/r.x/2018_07_10_newRC100/scatter2.png<]this graph[/url<], an note that the DRAM-less RC100 lists for the same price as the DRAM-assisted SX8200. Both of those drives "work" and both of those drives are "better than a mechanical drive" but they are not equal in performance/$. Not. Even. Close. I also know that consumers 'dont care about write speeds' but as a consumer, I edit many gigabytes GoPro footage and patch large multi-gigabyte game files on a regular basis. I also move/copy games from mechanical to SSD often enough that I don't want abysmal write performance. Sure, I also do a lot of non-consumer stuff on my PC which means I absolutely loate slow SSDs, but even when I take a step back and look solely at consumer loads on my drives, I wouldn't be satisfied with DRAM-less performance unless it was drastically cheaper than everything else - and by drastic, I mean "half price or lower" 🙁

          • Usacomp2k3
          • 6 months ago

          I agree with you that if the price is the them, then absolutely get the better one. We’ll have to see how it is priced when it rolls out. If it is more than 10% cheaper I would support it.

            • Chrispy_
            • 6 months ago

            Historically, the price has been about 0% cheaper. Take Crucial who have had the MX500 and BX500 in the market for some time now:

            MX500 = one of the best performing SATA drives on the market, for $140/TB
            BX500 = truly a turd; low application performance and low write speeds, for $135.50/TB

            At 3% cheaper you’re getting
            poor write speeds for anything sequential
            poor real-world copy speeds
            poor power efficiency (so bad for laptops)
            poor write endurance and high write amplification
            worst-in-class OS boot times
            worst-in-class application load times
            worst-in-class file indexing, compression, thumbnailing, and random file performance.
            worst-in-class antivirus/antimalware scanning performance

            Sure, it reads okay but that’s literally it. Don’t ever waste your money on this turd when better drives are on sale at pretty much exactly the same price.

      • TurtlePerson2
      • 6 months ago

      It’s been a few years since my last computer architecture course, but don’t computers already have DRAM on the motherboard to act as a “cache” for the hard drive? Why put additional DRAM in the hard drive to act as a mini-cache doing the same thing that main memory is doing? I’m sure you could create synthetic tests that will show this helping, but is it actually needed or is it just a gimmick?

        • UberGerbil
        • 6 months ago

        Those two kinds of cache are not doing the same thing. SSDs write NAND cells in blocks and have to erase those blocks before re-writing them; to do this efficiently with high-throughput the NAND controller needs a (fast) cache to buffer the data as it organizes the writes. The CPU has no awareness of the details of this, so the file-system caching that it is doing in system memory cannot help; meanwhile, the NAND controller has no access to system RAM across the SATA bus so it can’t use that either. In theory one could write a low-level driver to do something like this but it would be drive-specific… and do you really want your cheap SSD to require a driver (and do you really want the people responsible for that cheap SSD to be writing software that’s operating at the lowest levels of your system?) In practice the DRAM-less controllers simply throttle writes, especially once the never-written blocks have been used up and it is getting hit with enough new data that it is having to pause to zero out and garbage-collect old “erased” blocks. (At least now TRIM is pretty much ubiquitous so the controller actually knows which files-system-level blocks are “erased”)

        NVMe is a different beast: true NVMe SSDs that operate over PCIe (not the ones that “pretend” to be NVME by using the M.2 form factor but employ SATA/USB protocols) do get access to system memory (since PCIe devices can be cache-coherent peers) and can use that as cache, though they also tend to have their own DRAM anyway because the controller can still make use of it for block rewrite/organization purposes (essentially the same reason GPUs have their own on-board memory even though as PCIe peers they have access to system memory: board-local dedicated memory is faster and much lower-latency than shared memory hanging off the other end of a PCIe link).

          • Waco
          • 6 months ago

          While the importance in a consumer drive is vastly overrated, this is all true.

      • derFunkenstein
      • 6 months ago

      absolutely

      • ronch
      • 6 months ago

      Don’t you know that… a penny saved is a penny earned??

      /quack!!

      • juampa_valve_rde
      • 6 months ago

      My Sandforce SF-2281 based Corsair Force GT 240GB with MLC disagrees with you. Look mom, no DRAM!

        • Chrispy_
        • 6 months ago

        Still got one of those in this PC!

        Ah, the good old days of 8+ channels and low-latency MLC with enough bandwidth to saturate a SATA3 bus. They still actually make SSDs similar to those, for enterprise clients, if you’re willing to pay utterly ridiculous prices 😉

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