rados bench -p rbd 10 write
 Maintaining 16 concurrent writes of 4194304 bytes for up to 10 seconds or 0 objects
 Object prefix: benchmark_data_ceph1_2977
   sec Cur ops   started  finished  avg MB/s  cur MB/s  last lat   avg lat
     0       0         0         0         0         0         -         0
     1      16        94        78   311.821       312  0.041228  0.140132
     2      16       192       176   351.866       392  0.106294  0.175055
     3      16       275       259   345.216       332  0.076795  0.166036
     4      16       302       286   285.912       108  0.043888  0.196419
     5      16       395       379    303.11       372  0.126033  0.207488
     6      16       501       485   323.242       424  0.125972  0.194559
     7      16       621       605   345.621       480  0.194155  0.183123
     8      16       730       714   356.903       436  0.086678  0.176099
     9      16       814       798   354.572       336  0.081567  0.174786
    10      16       832       816   326.313        72  0.037431  0.182355
    11      16       833       817   297.013         4  0.533326  0.182784
 Total time run:         11.489068
Total writes made:      833
Write size:             4194304
Bandwidth (MB/sec):     290.015

Stddev Bandwidth:       175.723
Max bandwidth (MB/sec): 480
Min bandwidth (MB/sec): 0
Average Latency:        0.220582
Stddev Latency:         0.343697
Max latency:            2.85104
Min latency:            0.035381

rbdop1 ext4
time dd if=/dev/zero of=hello bs=4k count=25000 oflag=direct
25000+0 records in
25000+0 records out
102400000 bytes (102 MB) copied, 110.582 s, 926 kB/s

real    1m50.585s
user    0m0.106s
sys     0m2.233s