== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 20:47:16 (1784594836)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       19940     1251364   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       12400     1258904   1%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       21804     3585216   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       21744     3585276   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43548     7170492   1%  /mnt/lustre