Sequential Read Performance

Our first test of sequential read performance uses short bursts of 128MB, issued as 128kB operations with no queuing. The test averages performance across eight bursts for a total of 1GB of data transferred from a drive containing 16GB of data. Between each burst the drive is given enough idle time to keep the overall duty cycle at 20%.

Burst 128kB Sequential Read (Queue Depth 1)
Orange is for the new drives, Blue is for the previous generation models

The burst sequential read speeds of almost all of these SATA drives are essentially equivalent; the slightly lower scores from the new WD and SanDisk drives are not a meaningful drop from the previous generation.

Our test of sustained sequential reads uses queue depths from 1 to 32, with the performance and power scores computed as the average of QD1, QD2 and QD4. Each queue depth is tested for up to one minute or 32GB transferred, from a drive containing 64GB of data.

Sustained 128kB Sequential Read

On the longer test of sequential reads, the WD Blue 3D NAND and SanDisk Ultra 3D end up in the second tier of SSDs, tied with the Intel 545s and Toshiba's MLC-based OCZ VX500, but Samsung's 850 PRO and 850 EVO still have a substantial performance advantage.

Sustained 128kB Sequential Read (Power Efficiency)

The power efficiency of the WD Blue 3D NAND and SanDisk Ultra 3D is excellent, trailing behind only the MLC-based OCZ VX500 that also uses a reduced amount of external DRAM. The previous generation of SanDisk and WD drives had the same power efficiency as Samsung's 850 PRO and EVO, which was good by last year's standards.

From QD1 to QD2, the WD Blue 3D NAND and SanDisk Ultra 3D see a slight improvement in sequential read performance and don't benefit any further from higher queue depths. The Samsung 850 PRO and 850 EVO both show a much larger jump in performance from QD1 to QD2, leading to a higher steady-state sequential read speed. The OCZ VX500 can actually match the Samsung drives at high queue depths, but it doesn't saturate until QD4.

Sequential Write Performance

Our test of sequential write burst performance is structured identically to the sequential read burst performance test save for the direction of the data transfer. Each burst writes 128MB as 128kB operations issued at QD1, for a total of 1GB of data written to a drive containing 16GB of data.

Burst 128kB Sequential Write (Queue Depth 1)

As with sequential reads, the burst sequential write speed of the new WD and SanDisk drives is slightly reduced from the preceding generation, but the performance isn't low enough to make the new drives stand out from the crowd.

Our test of sustained sequential writes is structured identically to our sustained sequential read test, save for the direction of the data transfers. Queue depths range from 1 to 32 and each queue depth is tested for up to one minute or 32GB, followed by up to one minute of idle time for the drive to cool off and perform garbage collection. The test is confined to a 64GB span of the drive.

Sustained 128kB Sequential Write

The performance of the WD Blue 3D NAND and SanDisk Ultra 3D on the longer sequential write test is much improved from the previous generation of drives, but still rather slow compared to the competition.

Sustained 128kB Sequential Write (Power Efficiency)

With a substantial performance boost, the power efficiency of the latest WD/SanDisk SSDs is now about average, and is competitive with Samsung's drives but far lower than what the Crucial MX300 or OCZ VX500 offer.

The mediocre sustained sequential write performance of the new WD/SanDisk 3D NAND SSDs is due to a combination of relatively low performance once the drive has reached its full performance, and a slow ramp up that is still not quite at full speed by QD4. Most drives are operating at or very near their full performance at QD2.

Random Performance Mixed Read/Write Performance


View All Comments

  • MrSpadge - Thursday, September 14, 2017 - link

    The production cost is pretty much the same, be it SATA or PCIe. So "SATA being tapped" doesn't help price at all, except for the fact that manufacturers can't bill you for extra performance. But that was always the case with the slower SSDs. Reply
  • nathanddrews - Friday, September 15, 2017 - link

    I know it's not realistic, hence "it would just be nice if". Reply
  • CheapSushi - Sunday, September 17, 2017 - link

    V-NAND QLC will make that happen. I think for bulk storage, QLC SATA drives will be perfect for that duty and will decrease price per GB. Reply
  • Magichands8 - Thursday, September 14, 2017 - link

    Unfortunately, it's still about 3 times more expensive than it should be for it to be viable. Still wouldn't buy either as they're both crippled by the SATA interface but hey, at least they got the form factor right by offering them in 2.5". Reply
  • MajGenRelativity - Thursday, September 14, 2017 - link

    I'm not aware of any SSDs that are 1/3 the price, and there certainly aren't any that are 1/3 the price and have competitive performance. The SATA interface will not be going away for a while, and most people don't need the performance afforded by PCIe Reply
  • DanNeely - Thursday, September 14, 2017 - link

    I assume he's sulking because it's still about 5-6x as expensive as spinning rust. ($50 for the 1TB blue at 5400 RPM on amazon). I haven't seen any more recent projections but as of a a year ago the crossover in price per TB was predicted to occur in the mid 2020's; so we've still got a way to go. Reply
  • MajGenRelativity - Thursday, September 14, 2017 - link

    Fair point, but SSDs are still viable without a price drop, mass-market adoption is what requires the price drop Reply
  • Magichands8 - Friday, September 15, 2017 - link

    Oh I don't mind paying a premium for the SSD tech but I do mind the ridiculously inflated prices and performance bottlenecks that we've had to put up with for years and years. From the other posts here it's obvious that there are a lot of people comfortable with that though and willing if not eager to pay very high prices for low capacity and low performance drives even while manufacturers have had years to differentiate their products. Even when said people must know of the supply shortages and the impending lower prices only a matter of months away. Like I've said before, drives like these might be real last ditch options for people in a crunch who absolutely need a replacement drive immediately or perhaps some other niche reason. But otherwise it just doesn't make much sense. Reply
  • CheapSushi - Sunday, September 17, 2017 - link

    Are you saying this because you want to have ONE drive in your system to function as a performance panacea? I can see why someone would advocate for that particular setup if JUST a gamer with a mini-ITX system. But with ATX systems, there's nothing wrong with multiple drives; fom NVMe Optane, to NVMe PCIe to AHCI SATA, each have a place. Reply
  • Magichands8 - Sunday, September 17, 2017 - link

    EVERYONE should advocate for that setup. You're obviously very accustomed to think it natural for someone to have 3 or 4 different kinds of storage to achieve their goal(s). Are you telling me that if I offered you a single drive and interface that satisfied all of those rolls you would reject it? Are you actually advocating that computer users should be FORCED to compromise at every step of the way when they use their system? Reply

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