I've benchmarked about 10 diffrent ssd devices with sysbench oltp_write_only.lua and I found no coroleation whatsoever between max sustained write IOPS of device (both from specification and from fio --bs=4k --iodepth=64 benchmark). I've tested nvme ssds with sustained write IOPS of 90k but those were much slower in oltp_write_only.lua test than one particular 15k write IOPS sata ssd while similar to most other sata ssds. WHY? What makes some ssd peform better in sysbench oltp_write_only.lua test? Also why oltp_write_only.lua test does not perform significantly better when mysql datadir in on tmpfs? Why raid levels 0 (2 devices), 10 (4 devices) do not affect oltp_write_only results at all? It's madness. And no, its not a bug in specific MySQL/MariaDB version - I've tried many versions and results were consistent. And yes, devices were trimmed before each test.