== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 04:06:16 (1786953976)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       17260     1254044   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116        9772     1261532   1%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       30232     3576536   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       13364     3593544   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43596     7170080   1%  /mnt/lustre