Look at the hardware first: The hardware in the Ceph test is only capable of max 1.7TiB/s traffic (optimally without any overhead whatsoever). I also assume t

Look at the hardware first: The hardware in the Ceph test is only capable of max 1.7TiB/s traffic (optimally without any overhead whatsoever). I also assume that the batch size (block size) is different enough that this alone would make a big difference.