== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 23:34:34 (1786937674)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      2210304        9856     2198400   1%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3771392       23552     3743744   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3771392       26624     3740672   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7542784       50176     7484416   1%  /mnt/lustre