WD Black SN850X with Heatsink 2TB SSD Review

We used CrystalDiskMark 8‘s custom settings to test the 4K random write performance of the drive through a range of queue depths. The setup for the tests is listed below.

Transfer Request Size: 4KB, Outstanding I/O: 1-3

As with the 4K random read tests, the random write test results are well short of the official 1.1M IOPS, peaking at 362,876 IOPS (QD32). As with the random reads, we ran a test using eight threads at QD32 to see if we could closer to the official figure. The best we saw from the drive was 464,466 IOPS, an improvement, but nowhere close to the official figure.

4K Random Write v QD Performance.

At QD1, the 2TB SN850X is the fastest consumer drive we've tested to date with a test result of 213,859 IOPS. As the queue depth deepens the drive drops down the charts but at QD32 it stages a bit of a comeback.

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