== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 00:54:40 (1787806480)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       17256     1254048   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116        9704     1261600   1%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       25852     3581028   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       17704     3588924   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       43556     7169952   1%  /mnt/lustre