The Western Digital WD Black 3D NAND SSD Review: EVO Meets Its Match
by Ganesh T S & Billy Tallis on April 5, 2018 9:45 AM EST- Posted in
- SSDs
- Storage
- Western Digital
- SanDisk
- NVMe
- Extreme Pro
- WD Black
Random Read Performance
Our first test of random read performance uses very short bursts of operations issued one at a time with no queuing. The drives are given enough idle time between bursts to yield an overall duty cycle of 20%, so thermal throttling is impossible. Each burst consists of a total of 32MB of 4kB random reads, from a 16GB span of the disk. The total data read is 1GB.
The burst random read performance of the WD Black isn't exceptional, but it is an improvement over the original WD Black SSD and is only slightly behind the Samsung 960 EVO.
Our sustained random read performance is similar to the random read test from our 2015 test suite: queue depths from 1 to 32 are tested, and the average performance and power efficiency across QD1, QD2 and QD4 are reported as the primary scores. Each queue depth is tested for one minute or 32GB of data transferred, whichever is shorter. After each queue depth is tested, the drive is given up to one minute to cool off so that the higher queue depths are unlikely to be affected by accumulated heat build-up. The individual read operations are again 4kB, and cover a 64GB span of the drive.
The sustained random read performance of the WD Black is a small improvement over last year's model, but not quite enough to catch up to Samsung. In addition, the recent Intel 760p also comes out slightly ahead of the WD Black.
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| Power Efficiency in MB/s/W | Average Power in W | ||||||||
The power efficiency of the WD Black during random reads is better than any other TLC drive as it barely draws any more power than a SATA drive during this test.
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At higher queue depths, the Samsung drives build a small performance lead over the WD Black, but most other drives fall far behind as the queue depth increases.
Random Write Performance
Our test of random write burst performance is structured similarly to the random read burst test, but each burst is only 4MB and the total test length is 128MB. The 4kB random write operations are distributed over a 16GB span of the drive, and the operations are issued one at a time with no queuing.
Our WD Black sample oddly returned a substantially better burst random write score than the SanDisk Extreme PRO that should be identical. Since both scores are at the top of the chart, unusually high variance doesn't actually present a problem.
As with the sustained random read test, our sustained 4kB random write test runs for up to one minute or 32GB per queue depth, covering a 64GB span of the drive and giving the drive up to 1 minute of idle time between queue depths to allow for write caches to be flushed and for the drive to cool down.
The new WD Black offers top-tier performance on the sustained random write test, well ahead of Samsung's current retail offerings and just barely behind the PM981 OEM drive that Samsung's next generation retail drives will be based upon. Last year's WD Black was just barely faster than SATA drives.
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| Power Efficiency in MB/s/W | Average Power in W | ||||||||
The overhaul of the NAND and the controller has taken the WD Black from the bottom of the efficiency chart with last year's model to the very top, where it has a small lead over the Toshiba XG5 and Samsung 960 PRO.
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The WD Black's random write performance saturates at QD4 while the Samsung drives and several other models continue improving and can hit much higher performance levels at high queue depths. However, the WD Black has all the random write performance it needs at the more important low queue depths.
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Chaitanya - Thursday, April 5, 2018 - link
Nice to see some good competition to Samsung products in SSD space. Would like to see durability testing on these drives.HStewart - Thursday, April 5, 2018 - link
Yes it nice to have competition in this area and important thing to notice here a long time disk drive manufacture is changes it technology to meet changes in storage technology.Samus - Thursday, April 5, 2018 - link
Looks like WD's purchase of SanDisk is showing some payoff. If only Toshiba would have taken advantage of OCZ (who purchased Indilinx) in-house talent. The Barefoot controller showed a lot of promise and could have easily been updated to support low power states and TLC NAND. But they shelved it. I don't really know why Toshiba bought OCZ.haukionkannel - Friday, April 6, 2018 - link
Indeed! Samsung did have too long time performance supremesy and that did make the company to upp the prices (natural development thought).Hopefully this better situation help uss customers in reasonable time frame. Too much bad news to consumers last years considering the prices.
XabanakFanatik - Thursday, April 5, 2018 - link
Whatever happened to performance consistency testing?Billy Tallis - Thursday, April 5, 2018 - link
The steady state QD32 random write test doesn't say anything meaningful about how modern SSDs will behave on real client workloads. It used to be a half-decent test before everything was TLC with SLC caching and the potential for thermal throttling on M.2 NVMe drives. Now, it's impossible to run a sustained workload for an hour and claim that it tells you something about how your drive will handle a bursty real world workload. The only purpose that benchmark can serve today is to tell you how suitable a consumer drive is for (ab)use as an enterprise drive.iter - Thursday, April 5, 2018 - link
Most of the tests don't say anything meaningful about "how modern SSDs will behave on real client workloads". You can spend 400% more money on storage that will only get you 4% of performance improvement in real world tasks.So why not omit synthetic tests altogether while you are at it?
Billy Tallis - Thursday, April 5, 2018 - link
You're alluding to the difference between storage performance and whole system/application performance. A storage benchmark doesn't necessarily give you a direct measurement of whole system or application performance, but done properly it will tell you about how the choice of an SSD will affect the portion of your workload that is storage-dependent. Much like Amdahl's law, speeding up storage doesn't affect the non-storage bottlenecks in your workload.That's not the problem with the steady-state random write test. The problem with the steady state random write test is that real world usage doesn't put the drive in steady state, and the steady state behavior is completely different from the behavior when writing in bursts to the SLC cache. So that benchmark isn't even applicable to the 5% or 1% of your desktop usage that is spent waiting on storage.
On the other hand, I have tried to ensure that the synthetic benchmarks I include actually are representative of real-world client storage workloads, by focusing primarily on low queue depths and limiting the benchmark duration to realistic quantities of data transferred and giving the drive idle time instead of running everything back to back. Synthetic benchmarks don't have to be the misleading marketing tests designed to produce the biggest numbers possible.
MrSpadge - Thursday, April 5, 2018 - link
Good answer, Billy. It won't please everyone here, but that's impossible anyway.iter - Thursday, April 5, 2018 - link
People do want to see how much time it takes before cache gives out. Don't presume to know what all people do with their systems.As I mentioned 99% of the tests are already useless when it comes to indicating overall system performance. 99% of the people don't need anything above mainstream SATA SSD. So your point on excluding that one test is rather moot.
All in all, it seems you are intentionally hiding the weakness of certain products. Not cool. Run the tests, post the numbers, that's what you get paid for, I don't think it is unreasonable to expect that you do your job. Two people pointed out the absence of that tests, which is two more than those who explicitly stated they don't care about it, much less have anything against it. Statistically speaking, the test is of interest, and I highly doubt it will kill you to include it.