== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 00:31:51 (1786681911)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       11356     1259948   1%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       16232     1255072   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       26816     3579840   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       16760     3590176   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43576     7170016   1%  /mnt/lustre