When commissioning new Ceph clusters, our standard tests also include measuring the I/O latency for RBD.
We also always measure the performance values for the entire stack. Over the years, we have seen the results of our hard work in improving ceph osd in various tests.
For our tests, we create a temporary work file and read random blocks with non-cached read operations from it.
We are now measuring latencies of 300 to 600 microseconds.