== sanity test 56Db: test 'lfs df -m' only shows MDT devices ========================================================== 20:02:29 (1786838549)
UUID                   1K-blocks        Used   Available Use%  Mounted on
lustre-MDT0000_UUID      1414116       14500     1256804   2%  /mnt/lustre[MDT:0] 
lustre-MDT0001_UUID      1414116       18460     1252844   2%  /mnt/lustre[MDT:1] 
lustre-OST0000_UUID      3833116       31316     3575704   1%  /mnt/lustre[OST:0] 
lustre-OST0001_UUID      3833116       13260     3593760   1%  /mnt/lustre[OST:1] 

filesystem_summary:      7666232       44576     7169464   1%  /mnt/lustre