We used CrystalDiskMark 8‘s custom settings to test the 4K random read 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: 1-32.
The 2TB WD_Black SN770M is officially rated as up to 650,000 IOPS for random reads. Using our 4-threaded random read test we couldn't quite get to the official maximum as the best we saw was 591.267 IOPS (QD32).
4K Sustained Random Read v QD.
At QDs 1, 2 and 4 the drive languishes at the bottom of the results chart but at QD32 it rockets up to near the top of the table.