The Western Digital WD Black 3D NAND SSD Review: EVO Meets Its Match

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.

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.

Western Digital WD Black 1TB (3D NAND)Intel SSD 760p 512GBSamsung 960 EVO 1TBSamsung 960 PRO 1TBPatriot Hellfire 480GBSamsung PM981 1TBOCZ RD400 1TBADATA XPG SX8000 512GBWestern Digital WD Black 512GB (2D NAND)SanDisk Extreme Pro 1TBToshiba XG5 1TBSamsung 860 EVO 2TB M.2Crucial MX500 1TBSanDisk Ultra 3D 1TBIntel Optane SSD 900P 280GBWestern Digital WD Black 7200RPM 1TB

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.

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.

Western Digital WD Black 1TB (3D NAND)Intel SSD 760p 512GBSamsung 960 EVO 1TBSamsung 960 PRO 1TBPatriot Hellfire 480GBSamsung PM981 1TBOCZ RD400 1TBADATA XPG SX8000 512GBWestern Digital WD Black 512GB (2D NAND)SanDisk Extreme Pro 1TBToshiba XG5 1TBSamsung 860 EVO 2TB M.2Crucial MX500 1TBSanDisk Ultra 3D 1TBIntel Optane SSD 900P 280GBWestern Digital WD Black 7200RPM 1TB

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.