== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 04:37:10 (1786955830)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      2210048        8448     2199552   1%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3771392       22528     3731456   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3771392       26624     3738624   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7542784       49152     7470080   1%  /mnt/lustre