== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 02:00:09 (1787378409)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       11684     1259620   1%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       16356     1254948   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       22896     3584124   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       20712     3586308   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43608     7170432   1%  /mnt/lustre