== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 08:15:53 (1786536953)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       21284     1250020   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       15808     1255496   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       26928     3580092   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       18704     3588316   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       45632     7168408   1%  /mnt/lustre