== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 03:03:31 (1781247811)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       19236     1252068   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       11872     1259432   1%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       22696     3584324   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       20856     3586164   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43552     7170488   1%  /mnt/lustre