Conclusion

The WD Blue SN500 defies expectations. Its basic specifications say it's an entry-level NVMe drive: only two PCIe lanes (so it can't possibly exceed 2GB/s), a DRAMless controller that isn't using the NVMe Host Memory Buffer feature either, and a tiny SLC write cache. And our review sample is a 250GB model, which is the smallest drive capacity that can come close to offering decent performance when using just a handful of modern high-capacity NAND flash dies.

What we are accustomed to seeing from low-end NVMe drives is peak performance that's impressively high compared to SATA, but with caveats in the form of severely reduced performance in suboptimal conditions. What makes or breaks a low-end DRAMless SSD (even on NVMe) is usually not the question of how abysmal its worst case performance is, but whether that worst-case performance can be avoided during real-world usage.

The WD Blue SN500 doesn't buckle under the pressure of our most intense tests, and it performs surprisingly well on The Destroyer even when compared against some high-end NVMe models of similar capacity. The SN500's SLC cache is tiny, but the performance after the cache is full is pretty good for a 250GB drive, and it's not noticeably interrupted or degraded by garbage collection cycles. Compared to the other small entry-level NVMe SSDs we've tested, the SN500 is a clear winner. It doesn't come out ahead in every single test, but the overall performance profile is much more consistent. The SN500 at its worst is still a decent SSD.

The WD Blue SN500 is not a high-end NVMe drive and it is not at all hard to find cases where the typical high-end NVMe drive with a PCIe x4 connection is much faster than the SN500. But on the tests with more realistic IO patterns, the gap between the SN500 and the top tier of drives isn't huge.

Western Digital was late to the game with in-house NVMe SSD controllers, but they clearly took the time to get it right. Both the high-end WD Black and mainstream WD Blue SSD product lines (and their OEM counterparts) are now using controllers based on their own controller architecture, and both instantiations of that architecture seem to be very successful for a first-generation release. The two products offer very different performance, but most of the time they have very similar power efficiency that puts them at or near the top of the charts. For the slower WD Blue SN500, that excellent efficiency usually means it's drawing less than 2W under load, though it can occasionally be pushed all the way up to 2.5W. The OEM drive that the SN500 is derived from was intended to fit into the thinnest and lightest notebooks and tablets, and it looks like Western Digital achieved that goal without making any horrible sacrifices (except to maximum drive capacity).

We didn't have a 250GB sample of the older SATA-based WD Blue SSD on hand to compare against, but the 250GB SN500 had no trouble matching or exceeding the performance of the 1TB WD Blue SATA SSD. Since performance generally scales with capacity, this is an illustration both of how good the SN500 is and how ready the mainstream SSD market segment is to break free of the limitations of a SATA interface.

At current pricing, the WD Blue SN500 isn't quite ready to push SATA SSDs out of the market, but it does make it very easy to step up to NVMe without regrets or worries. However, as usual there are some even faster drives for sale in basically the same price range, including the HP EX920 (Silicon Motion SM2262) and the Team MP34 (Phison E12 controller) that we will be reviewing soon. If Western Digital can push the price of their entry-level NVMe drive all the way down to SATA prices, they'll have a very successful product on their hands.

Power Management
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  • willis936 - Saturday, April 20, 2019 - link

    I'm surprised there isn't a significant difference in idle power consumption or drive-side efficiency for a DRAMless NVMe drive. This is a pretty nice piece of hardware, regardless of price. Reply
  • DyneCorp - Saturday, April 20, 2019 - link

    Thanks for the review, Billy! I really appreciate your work; you always do an excellent job and I appreciate you taking time out of your life to throw these reviews up.

    Without the DRAM buffer, how do you think write amplification is affected? Obviously endurance is actually quite high (in SU800 territory) and performance is quite high. This is especially interesting considering how small the SLC cache buffer is.

    Do you think WD has effectively mitigated negative endurance impact through firmware?
    Reply
  • gglaw - Saturday, April 20, 2019 - link

    There really is no market segment for this drive unless the WD name is enough to sway a lot of customers. Pretty much every week there's an EX920 or Adata 8200 500GB drive for between $70-$80 and they are superior to this drive in every way. You could nitpick on brand reliability, etc, but both those drives have an incredible track record in the last couple years.

    For a primary OS/Apps drive, I would get the faster HP/Adata for a few bucks more, and for a games/storage drive I would get the cheapest SATA I could find (usually an Adata 1TB for $90). Can't think of any scenario I would get a budget NVME over one of these options. This WD drive would have to drop to $60 to be a real contender.
    Reply
  • DyneCorp - Sunday, April 21, 2019 - link

    There's absolutely a market.

    The SN500 will drop in price drastically. It also will stand out when prices increase, as they always do. Just as QLC dropped in price, just as 3D NAND dropped in price.

    Why you people have to drop negative comments about a product that was just released, I'll never understand. It always drops in price. First world problems, my son.

    By the way, spending "a few bucks more" for an overkill drive makes no sense. The SN500 is more than capable as an OS drive.

    Realistically, WD releasing the SN500 provides more competition and that will lower prices. I really don't understand what your issue is.
    Reply
  • Cisco Guy 318 - Sunday, April 21, 2019 - link

    Abismal endurance! What happened to petabyte endurance? MLC is bad enough but the newer chips have poor endurance! Reply
  • FunBunny2 - Sunday, April 21, 2019 - link

    to paraphrase an ancient consultants' adage: "speed, endurance, capacity; choose two". Reply
  • DyneCorp - Sunday, April 21, 2019 - link

    Except that 64-layer 3D TLC NAND has exceeded planar MLC in every metric? Reply
  • FunBunny2 - Sunday, April 21, 2019 - link

    for now, I suppose. so long as TLC is fabricated on 40-50nm, perhaps so. capitalist greed will, in due time, impel vendors to drop down to contemporary nodes in search of capacity. what then? or, is it, now?

    Mr Tallis: true of speed and endurance?
    Reply
  • DyneCorp - Sunday, April 21, 2019 - link

    Except that 64-layer 3D NAND (and up) from Samsung and Micron/ Intel is at 20nm and Toshiba/ Western Digital is at 19nm. You understand planar TLC basically ceased at 14-15nm?

    Back in 2016, with the advent of smart SLC caching techniques in addition to intelligent controller firmware, SSDs utilizing 3D NAND effectively outpaced 2D "planar" MLC. In fact, the 660p (utilizing 3D QLC) can perform on par (in certain metrics) with SSDs utilizing MLC because of Intel's intelligent pSLC caching strategies.

    In the end, it doesn't matter. You'll never chew through the endurance of a modern SSD when subjecting it to consumer workloads, period. The controller can effectively mitigate write amplification in most circumstances.
    Reply
  • DyneCorp - Sunday, April 21, 2019 - link

    Abysmal endurance? Far from it. The SN500 carries an endurance rating far above the Samsung 850 EVO and is in SU800 territory; its endurance rating is actually quite high, comparatively.

    You do understand that just about any SSD utilizing 3D NAND has endurance ratings far beyond what 2D planar MLC SSDs had?

    Most importantly, remember this: endurance doesn't matter for consumer drives. SSDs last far beyond their warranted endurance life.It's been tested.

    Why is this? Because modern controllers can effectively mitigate write amplification by several factors. The majority of consumer workloads will NEVER burn through rated endurance, period. Honestly, including a TBW rating is unnecessary.
    Reply

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