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 ADATA SP550 120 SSD is rated at 60k IOPS for the 4K Random Read and 70k IOPS for the 4K Random Write. We were hitting 57k on the reads, but much lower on the writes as our testing fills up the SLC cache. The ADATA SP550 240GB SSD is rated for 75k IOPS both R/W and we hit that almost exactly on the read test!
When it comes to MBps you are looking at 232MB/s on the 4KB Random Reads and 74 MB/s on the 4KB Random writes for the ADATA SP550 120GB SSD. Moving up to the larger 240GB drive will yield faster 4KB Random Reads speeds of 307 MB/s and 102 MB/s for the 4KB Random writes.
The write response times on the ADATA SP550 240GB drive were found to be much lower than the SP550 120GB drive.