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 Toshiba OCZ RD400 512GB SSD is rated at 190k IOPS for the 4K Random Read and 120,000 IOPS for the 4K Random Write. Our testing showed that we were only able to get 272,607 IOPS read and 156,455 IOPS write on our pre-filled drive right after a secure erase was complete. This is higher than the performance specifications for the drive, so we are happy to see these results.
When it comes to MBps you are looking at ~641 MB/s on the 4KB Random Reads and 1117 MB/s on the 4KB Random writes for the Toshiba OCZ RD400 512GB SSD. The 4K random read scores are slightly lower than the Samsung SSD 950 PRO 512GB drive, but the 4K random writes were nearly double!
The response times on the Toshiba OCZ RD400 512GB SSD were great with 0.47ms read and 0.82ms write.