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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  • tipoo - Friday, April 19, 2019 - link

    I'd still be interested in seeing a T2 SSD (Apple) put through these paces. Usually they did great in sequential tests but not so much in 4k randoms, so I wonder how it would do on, say, Destroyer. Reply
  • kpb321 - Friday, April 19, 2019 - link

    This drive did exceed my expectations for a x2 pci-e lanes with no Dram and no HBM but the pricing is going to be key. The SM2262 drives have gotten pretty inexpensive and don't leave a lot of room for a drive like this even as good as it may be for what it is. I just recently picked up the ADATA version of the HP EX920 @ $73 for the 480gb drive. That a x4 drive with dram on it and should beat this drive pretty consistently. Personally this drive would need to be down around $60 before I'd consider the price difference meaningful enough to consider this drive. Reply
  • DyneCorp - Sunday, April 21, 2019 - link

    You got the EX920 512GB on sale. That's not the typical retail price, and the SN500 is already sitting at $65 retail.

    You understand the price of this drive will go down? As they always do after initial release? And when the prices of NAND skyrocket again, the SN500 will have a major advantage?

    For the majority of consumers, the SN500 is a viable option.
  • airider - Friday, April 19, 2019 - link

    This is WD clearing out their inventory while making way for the higher capacity/performance versions coming out shortly. Don't expect to see this product anymore by the end of 2019. Reply
  • flyingpants265 - Saturday, April 20, 2019 - link

    Wait, so it's not QLC nand? That's great. It states 300TB write endurance, compared to the 100TB of the 500gb Crucial P1, for the same price. Goodbye, QLC! For now.. Reply
  • DyneCorp - Sunday, April 21, 2019 - link

    For consumers, the endurance rating matters none. You'll never chew through 100TB of endurance, especially under consumer workloads. The massive SLC cache buffers utilized in the P1 and 660p in addition to smart caching algorithms increase endurance substantially. Also, the DRAM buffer in addition to smart controller firmware effectively mitigate write amplification by several factors. You'll never chew through the endurance of the P1 or the 660p, period.

    Endurance ratings are meaningless under consumer workloads. SSDs far outlast their given endurance ratings.
  • flyingpants265 - Wednesday, April 24, 2019 - link

    Well, hopefully. Because just to download install one game (hitman 2) requires about 240GB of writes. If I do that 3 times, that's 1% of my drive's life gone. Reply
  • flyingpants265 - Wednesday, April 24, 2019 - link

    Uh, 4 times. Reply
  • DyneCorp - Wednesday, April 24, 2019 - link

    This is incorrect. 240GB of writes does not equal 240GB of endurance lost, especially if they are sequential writes because:

    1.) The controller can reduce write amplification by intelligently shifting data around

    2.) Sequential writes to the SLC cache increase endurance significantly

    3.) Folding blocks from the pSLC cache to QLC actually increases endurance
  • DyneCorp - Wednesday, April 24, 2019 - link

    By the way, this is evidenced by the ADATA SU800. It has a massive dynamic SLC cache buffer and older Micron 32-layer 384-Gbit NAND and still carries the highest endurance rating on the market. Reply

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