Our 4KB random performance test is conducted in the same manner as our sequential tests, but once the drive is conditioned we run our saved random test profile that runs our 4KB test for two minutes without any idle time in between the tests. The queue depth is set to 32 on four workers and the test is begun. To get the benefits from NVMe based drives you must use multiple CPU queues and this is why we are now using four workers for this IOMeter test.
IOPS is the main thing we are looking at in this test scenario and the 850 PRO 2TB drive is rated at 100k IOPS for the 4K Random Read while the 850 EVO 2TB drive has a slightly lower rating of 98k IOPS. Both drives are rated at 90,000 IOPS for the 4KB Random Writes. On our conditioned drives we hit ~98,000 IOPS Read and ~87,000 IOPS Write. Both drives are performing nearly the same!
When it comes to MBps you are looking at ~400 MB/s on the 4KB Random Reads and ~356 MB/s on the 4KB Random writes.
The response times on the Samsung SSD 850 EVO and 850 PRO 2TB SATA III SSDs were below 1.5ms for both read and write operations, which is great for a SATA drive.