That is why I asked, I am only aware of the use of IOPS in connection with disk I/O and it seems a rather unusual measure for a database where caches hopefully avoid hitting the disk too often, at least for reads. And writing 8 MiB/s assuming 4k clusters seems not really noteworthy especially given three fold redundancy. On the other hand reading 700 MiB/s per second which would also not be affected by the redundancy seems a comparatively big number especially because caches should limit the disk traffic to a small fraction.