[root@pfs2n18 ~]# cat /proc/fs/lustre/osd-ldiskfs/pfs2wor2-OST0007/quota_slave/acct_user
usr_accounting:
- id:      0
  usage:   { inodes:               371162, kbytes:                15864 }
- id:      15214
  usage:   { inodes:                    4, kbytes:                 3292 }
- id:      900204
  usage:   { inodes:                    1, kbytes:                44776 }
- id:      10256
  usage:   { inodes:                  253, kbytes:              5014252 }
- id:      11557
  usage:   { inodes:                   50, kbytes:                38724 }
- id:      19493
  usage:   { inodes:                   16, kbytes:              1079924 }
- id:      828427392
  usage:   { inodes:                    2, kbytes:                    4 }
- id:      7587
  usage:   { inodes:                  166, kbytes:             65503220 }
- id:      18853
  usage:   { inodes:                39774, kbytes:             14975492 }
- id:      27944
  usage:   { inodes:                   11, kbytes:                16000 }
- id:      26598
  usage:   { inodes:                 1366, kbytes:              3159864 }
- id:      900857
  usage:   { inodes:                   46, kbytes:              1838088 }
- id:      900554
  usage:   { inodes:                   21, kbytes:                16652 }
- id:      900425
  usage:   { inodes:                   38, kbytes:               124216 }
- id:      208140
  usage:   { inodes:                 2174, kbytes:              7369144 }
- id:      208714
  usage:   { inodes:               237017, kbytes:             71452024 }
- id:      900568
  usage:   { inodes:                 2678, kbytes:             35140796 }
- id:      900104
  usage:   { inodes:                  580, kbytes:              2355272 }
- id:      3512
  usage:   { inodes:                    4, kbytes:              1497184 }
- id:      9009
  usage:   { inodes:                   91, kbytes:            199285600 }
- id:      202981
  usage:   { inodes:                 2522, kbytes:              4762700 }
- id:      900756
  usage:   { inodes:                  772, kbytes:               564640 }
- id:      900803
  usage:   { inodes:                    4, kbytes:                   20 }
- id:      900040
  usage:   { inodes:                 2926, kbytes:              5546856 }
- id:      900497
  usage:   { inodes:                   38, kbytes:               418512 }
- id:      28479
  usage:   { inodes:                  697, kbytes:               370084 }
- id:      211435
  usage:   { inodes:                 2547, kbytes:              1902148 }
- id:      210889
  usage:   { inodes:                    1, kbytes:                 1024 }
- id:      900494
  usage:   { inodes:                    1, kbytes:                    4 }
- id:      206072
  usage:   { inodes:                  108, kbytes:                29388 }
- id:      23337
  usage:   { inodes:                    1, kbytes:                    4 }

# Check sum: 
[root@pfs2n18 ~]# cat /proc/fs/lustre/osd-ldiskfs/pfs2wor2-OST0007/quota_slave/acct_user | perl -e '$sum = 0; while (<STDIN>) {if ( /kbytes:\s*(\d+)\s+/ ) {$sum += $1};}; print "Sum: $sum\n";'
Sum: 422768496

# On a client: 
bash-4.1$ lfs df /pfs/work2 | egrep "pfs2wor2-OST0007_UUID|Avail"
UUID                   1K-blocks        Used   Available Use% Mounted on
pfs2wor2-OST0007_UUID 22896358720   591165536 22075736180   3% /pfs/work2[OST:7]

# There is a difference of more than 100 GB!