[root@pfs2n18 ~]# cat /proc/fs/lustre/osd-ldiskfs/pfs2wor2-OST0007/quota_slave/acct_user
usr_accounting:
- id:      0
  usage:   { inodes:              1077664, kbytes:            151053400 }
- id:      3512
  usage:   { inodes:                    4, kbytes:              1497184 }
- id:      3529
  usage:   { inodes:                    9, kbytes:              1374448 }
- id:      7587
  usage:   { inodes:                  672, kbytes:            468648424 }
- id:      7625
  usage:   { inodes:                  414, kbytes:              2484908 }
- id:      9009
  usage:   { inodes:                  148, kbytes:            495689212 }
- id:      10132
  usage:   { inodes:                   52, kbytes:                  484 }
- id:      10256
  usage:   { inodes:                  346, kbytes:              5183528 }
- id:      11262
  usage:   { inodes:                  710, kbytes:               176204 }
- id:      11557
  usage:   { inodes:                   50, kbytes:                38724 }
- id:      15214
  usage:   { inodes:                   11, kbytes:                 3416 }
- id:      16887
  usage:   { inodes:               108606, kbytes:             59829144 }
- id:      17105
  usage:   { inodes:                13979, kbytes:              1093396 }
- id:      18853
  usage:   { inodes:               119994, kbytes:             40889024 }
- id:      19493
  usage:   { inodes:                   16, kbytes:              1079924 }
- id:      21869
  usage:   { inodes:                 1961, kbytes:                10208 }
- id:      22469
  usage:   { inodes:                22404, kbytes:              4586792 }
- id:      26598
  usage:   { inodes:                 1369, kbytes:              3169032 }
- id:      27944
  usage:   { inodes:                   12, kbytes:                21752 }
- id:      28479
  usage:   { inodes:                21424, kbytes:              5639168 }
- id:      40182
  usage:   { inodes:                    4, kbytes:              9969644 }
- id:      202981
  usage:   { inodes:                26616, kbytes:             28901092 }
- id:      206072
  usage:   { inodes:                  108, kbytes:                29388 }
- id:      207206
  usage:   { inodes:                 4825, kbytes:               614744 }
- id:      208140
  usage:   { inodes:                 2178, kbytes:              7808376 }
- id:      208714
  usage:   { inodes:               591805, kbytes:             78638956 }
- id:      210889
  usage:   { inodes:                    1, kbytes:                 1024 }
- id:      211314
  usage:   { inodes:                 5105, kbytes:              3903448 }
- id:      211435
  usage:   { inodes:                85429, kbytes:            163453920 }
- id:      890005
  usage:   { inodes:                    1, kbytes:                    4 }
- id:      900020
  usage:   { inodes:                    3, kbytes:             16777228 }
- id:      900029
  usage:   { inodes:                    1, kbytes:                   12 }
- id:      900040
  usage:   { inodes:                36262, kbytes:             93467504 }
- id:      900044
  usage:   { inodes:                    5, kbytes:                  328 }
- id:      900104
  usage:   { inodes:                  580, kbytes:              2355272 }
- id:      900204
  usage:   { inodes:                    1, kbytes:                44776 }
- id:      900425
  usage:   { inodes:                   66, kbytes:               151384 }
- id:      900470
  usage:   { inodes:                    2, kbytes:                   16 }
- id:      900494
  usage:   { inodes:                   17, kbytes:                 1516 }
- id:      900497
  usage:   { inodes:                 1160, kbytes:              1637816 }
- id:      900554
  usage:   { inodes:                  181, kbytes:             10279280 }
- id:      900568
  usage:   { inodes:                 4299, kbytes:            194190024 }
- id:      900655
  usage:   { inodes:                  299, kbytes:              3817972 }
- id:      900705
  usage:   { inodes:                   29, kbytes:                 7348 }
- id:      900715
  usage:   { inodes:                 3402, kbytes:             74428316 }
- id:      900740
  usage:   { inodes:                  170, kbytes:               137216 }
- id:      900756
  usage:   { inodes:                17004, kbytes:              1904292 }
- id:      900803
  usage:   { inodes:                    5, kbytes:                   24 }
- id:      900806
  usage:   { inodes:                 8805, kbytes:              6072908 }
- id:      900857
  usage:   { inodes:                  141, kbytes:              4528820 }
- id:      900883
  usage:   { inodes:                   62, kbytes:               844156 }
- id:      900910
  usage:   { inodes:                  179, kbytes:              6230128 }
- id:      901083
  usage:   { inodes:                    3, kbytes:                 1028 }
- id:      901152
  usage:   { inodes:                   13, kbytes:                 9568 }
- id:      901169
  usage:   { inodes:                   50, kbytes:               183812 }
- id:      901173
  usage:   { inodes:                   48, kbytes:               121556 }
- id:      901201
  usage:   { inodes:                   22, kbytes:              1490992 }
- id:      901296
  usage:   { inodes:                   31, kbytes:                54608 }
- id:      828427392
  usage:   { inodes:                    1, kbytes:                    0 }
- id:      888726912
  usage:   { inodes:                    4, kbytes:                    8 }

# 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: 1954504260

# 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  1955028628 20711897560   9% /pfs/work2[OST:7]

# The difference is now less than 1 GB.