== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 07:02:33 (1787396553)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       19444     1251860   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       11648     1259656   1%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       23736     3583200   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       19864     3587016   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43600     7170216   1%  /mnt/lustre