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

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%.

The WD Black offers great mixed random I/O performance, but it is still slightly slower overall than the best drives from Samsung, and the Optane SSD is in an entirely different league.

Power Efficiency in MB/s/W	Average Power in W

The WD Black's power efficiency on the mixed random I/O test is about the same as that of the Samsung 960 PRO, and close to the Optane SSD in spite of the vast difference in absolute performance level.

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 performance of the WD Black grows very slowly as the workload shifts from reads toward writes, but near the end of the test the good SLC write caching implementation gives the WD Black steep gains. Power consumption is under 2W for most of the test and doesn't quite reach 4W at the very end.

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.

The mixed sequential workload performance of the WD Black is surprisingly good, just barely behind the Optane SSD and far ahead of almost all flash-based SSDs.

Power Efficiency in MB/s/W	Average Power in W

The WD Black draws about the same power as other SSDs during the mixed sequential test, and combined with the great performance that translates to a huge lead in power efficiency.

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 performance scaling pattern of the WD Black on the mixed sequential test is quite unusual. Many drives show a bathtub curve with peak performance at either end of the test when the workload is pure reads or pure writes, and the worst performance in the middle of the test. By contrast, the WD Black starts out rather slowly but rapidly speeds up during the first half of the test, and stays near full performance for the entire second half.