== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 02:25:32 (1786947932)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      2210176        9472     2198656   1%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3771392       22528     3726336   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3771392       26624     3742720   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7542784       49152     7469056   1%  /mnt/lustre