== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 20:02:42 (1786838562)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       23428     1247876   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       17552     1253752   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       33184     3573836   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       12300     3594720   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       45484     7168556   1%  /mnt/lustre