== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 02:48:32 (1786430912)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       11516     1259788   1%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       16392     1254912   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       24748     3582272   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       18800     3588220   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43548     7170492   1%  /mnt/lustre