== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 06:04:06 (1785405846)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      2210048        7552     2200448   1%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3771392       23552     3738624   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3771392       24576     3740672   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7542784       48128     7479296   1%  /mnt/lustre