== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 03:01:24 (1781247684)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       16572     1254732   2%  /mnt/lustre[MDT:0] 
lustre-OST0000_UUID      3833116       21628     3585392   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       21372     3585648   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43000     7171040   1%  /mnt/lustre