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$ 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.


  • Slackware 13.37.0
  • Linux #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
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migrated from May 14 '12 at 20:21

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Hello BiFo. This is a programming Q&A site, not a general support forum. Please use a search engine, this type of question is asked (and answered) a lot. – Mat May 14 '12 at 19:03
Possibly a portion of the filesystem capacity was automatically reserved for the superuser? Or you have some cleverly hidden something on there, or a broken filesystem. – Chris Stratton May 14 '12 at 19:19
Try bind mounting your file system and see if there are any files hidden behind your mount points. – Dennis Williamson May 14 '12 at 22:35
See (and tons of other similar discussions). – Daniel Andersson May 15 '12 at 7:01

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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