struggling to achieve high bandwidth on Ceph dev cluster - HELP

Hi, Hello I am using rados bench tool. Currently I am using this tool on the development cluster after running vstart.sh script. It is working fine and I am interested in benchmarking the cluster. However I am struggling to achieve a good bandwidth i.e. bandwidth (MB/sec). My target throughput is at least 50 MB/sec and more. But mostly I am achieving is around 15-20 MB/sec. So, very poor. I am quite sure I am missing something. Either I have to change my cluster through vstart.sh script or I am not fully utilizing the rados bench tool. Or may be both. i.e. not the right cluster and also not using the rados bench tool correctly. Some of the shell examples I have been using to build the cluster are bellow: MDS=0 RGW=1 ../src/vstart.sh -d -l -n --bluestore MDS=0 RGW=1 MON=1 OSD=4../src/vstart.sh -d -l -n --bluestore While using rados bench tool I have been trying with different block sizes 4K, 8K, 16K, 32K, 64K, 128K, 256K, 512K. And I have also been changing the -t parameter in the shell to increase concurrent IOs. Looking forward to help. Bobby