== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 04:31:18 (1786177878)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      2210048        8192     2199808   1%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3771392       22528     3746816   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3771392       26624     3742720   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7542784       49152     7489536   1%  /mnt/lustre