Linux – df reported size/used/available discrepancy

dflinux

$ df -h
Filesystem                      Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-Backups  425G  377G   27G  94% /Backups
  • Size = 425G
  • Used = 377G
  • Available = 27G
  • Used + Available = 404G != 425G

Why is used+available different from total size? This is not happening in any other
server.

I've tried remounting and rebooting the system.

du shows that the "Used" space in the /Backups directory from the df
command is correct.

Details:

  • Slackware 13.37.0
  • Linux 2.6.37.6-smp #1 SMP Sat Apr 9 14:01:14 CDT 2011 i686 Intel(R) Xeon(R) CPU E5530 @ 2.40GHz GenuineIntel GNU/Linux
  • HP DL360 G6

Best Answer

This is most likely due to reserved space for the super-user on an ext2/ext3/ext4 filesystem, plus a small rounding error when converting blocks to gigabyte sizes. See this similar discussion.

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