== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 18:18:46 (1786486726)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       12824     1258480   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       17180     1254124   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       32136     3574884   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       11448     3595572   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43584     7170456   1%  /mnt/lustre