== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 02:36:30 (1786084590)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      2210048        8064     2199936   1%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3771392       22528     3724288   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3771392       26624     3733504   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7542784       49152     7457792   1%  /mnt/lustre