Mixed Random Performance

Our test of mixed random reads and writes covers mixes varying from pure reads to pure writes at 10% increments. Each mix is tested for up to 1 minute or 32GB of data transferred. The test is conducted with a queue depth of 4, and is limited to a 64GB span of the drive. In between each mix, the drive is given idle time of up to one minute so that the overall duty cycle is 50%.

Mixed 4kB Random Read/Write

The overall mixed random IO performance of the Western Digital WD Black SN750 is about the same as the previous version, as well as the Toshiba XG6 and HP EX920. These are the second-tier drives that are a bit slower than the SM2262EN and the Samsung 970 EVO.

Sustained 4kB Mixed Random Read/Write (Power Efficiency)
Power Efficiency in MB/s/W Average Power in W

The SN750 and the Toshiba XG6 have almost exactly the same overall performance on this test, but the XG6 has 7% better performance per Watt. The second place score of the SN750 is still well above average—ignoring the outgoing WD Black, the SN750's performance per Watt is about 26% better than the next best TLC drive.

The two flash-based drives that substantially outperform the SN750 on the mixed random IO test are faster through almost all of the test's phases, while the drives that are roughly tied with the SN750 tend to be a bit faster through the more read-heavy parts of the test and fall behind when the workload becomes very write-heavy.

Mixed Sequential Performance

Our test of mixed sequential reads and writes differs from the mixed random I/O test by performing 128kB sequential accesses rather than 4kB accesses at random locations, and the sequential test is conducted at queue depth 1. The range of mixes tested is the same, and the timing and limits on data transfers are also the same as above.

Mixed 128kB Sequential Read/Write

The WD Black SN750 improves upon its predecessor's performance on the mixed sequential IO test, but not quit enough to take the top spot on the performance ranking. The Samsung 970 EVO is a few percent faster overall.

Sustained 128kB Mixed Sequential Read/Write (Power Efficiency)
Power Efficiency in MB/s/W Average Power in W

The SN750 has a clear lead in the efficiency scores, improving upon the previous record set by last year's model that remained largely unchallenged, though the Toshiba XG6 and Corsair MP510 did come close. The average power consumption of the SN750 is slightly higher than the previous WD Black but that is more than offset by the higher average performance.

The WD Black SN750 only barely drops below 1.5GB/s at its worst during the mixed sequential IO test, and it performs a bit better during the more read-heavy half of the test. The other drives all have worst-case performance that's slower than the SN750 by at least a few hundred MB/s, but many of those drives also have significantly better peak performance, most often at the read-heavy end of the test.

Sequential Performance Power Management
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  • nevcairiel - Friday, January 18, 2019 - link

    Whatever happend to the Samsung PRO in those comparisons? If you call something a "top NVMe SSD" and then don't have the PROs in there to stack up against, it feels incomplete. Reply
  • jordanclock - Friday, January 18, 2019 - link

    Where do you see that they call it the top NVMe SSD?

    Comparing it to the 970PRO doesn't make a lot of sense since they are in vastly different price ranges and market segment. The 970 EVO is perfect because they are very close in price and market segment. They even admit in the conclusion that the "970 EVO may be the slightly better performer overall."
    Reply
  • Drakkhen - Friday, January 18, 2019 - link

    He didn't call it the top NVMe SSD, he said a "top NVMe SSD".

    But, I agree that it isn't really relevant since this comparison is for a different price point/market.
    Reply
  • DanNeely - Friday, January 18, 2019 - link

    I would like to see at at least on higher end drive that's not an Optane for comparison though. Reply
  • romrunning - Friday, January 18, 2019 - link

    Agreed Reply
  • philehidiot - Saturday, January 19, 2019 - link

    I think it's always useful, regardless of where you are in the meerkat, to compare to the top and the bottom of the range. This gives you an idea of what you're getting. Am I getting 70% of top end performance for 70% of the price or am I getting 95% of it for 70% of the price? Those are two very different value propositions and certainly things we see often in the PC meerkat. Sometimes the progression with price is linear(ish) and sometimes you can spend double the cash to get the very best but really all you're seeing is a few percent extra performance because it takes that much extra R&D / materials investment to get there. Reply
  • 29a - Friday, January 18, 2019 - link

    In the second paragraph on the last page.

    "the new WD Black is still a very competitive high-end NVMe SSD"

    They do make the claim that it is a high end SSE which I would equate to being "a top NVMe SSD" and should be compared to the Samsung Pro models.
    Reply
  • althaz - Friday, January 18, 2019 - link

    Depends where you are I guess. The 500Gb WD Black is exactly the same price as the 512Gb Samsung 970 Pro where I live. Samsung's 970 EVO drives are $100/TB cheaper. Reply
  • Samus - Monday, January 21, 2019 - link

    LOL, the 500GB WD Black is consistently close to half the price of the 980 Pro, and the 970 Pro is essentially the same performance as the EVO (hence them being similarly priced.)

    I agree, the 980 Pro should be in the benchmarks, but certainly not the 970 Pro. Just use the EVO as a baseline and add 3% if you want to be picky about exact figures.
    Reply
  • Samus - Monday, January 21, 2019 - link

    I forgot to add, or rather point out, the 970 EVO and 970 PRO share the same controller and are otherwise identical configurations with the exception of the PRO being MLC.

    That said, Samsung actually rates them near-identically in performance and aside from the SLC caching algorithm, the EVO performs the same.

    The only real reason to get the PRO is if you need the DWPD\endurance of MLC. That's literally the only advantage the PRO has.
    Reply

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