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I have a Linux CentOS server, the OS+packages used around 5GB. Then, I transferred 97GB data from a Windows server to two folders on this Linux server, after calculated the disk usage, I see the total size of the two folders is larger than the disk used size.

Run du -sh on each folder, one use 50GB, the other one use 47GB

But run df -h, the used space is 96GB. (50GB + 47GB + 5GB) > 96GB

Is there any problem? Those two folders contain lots of files (1 million+). Thanks.

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2 Answers 2

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This page gives some insight on why they have different values, however it seems to suggest that your du size should be the smaller of the two.

df uses total allocated blocks, while du only looks at files themselves, excluding metadata such as inodes, which still require blocks on the disk. Additionally, if a file is deleted while an application has it opened, du will report it as free space but df does not until the application exits.

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  • this explains why df claims the disk is full... when it's not.
    – xenoterracide
    Mar 19, 2011 at 7:43
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    your comment is incorrect. if df says the disk is full, it is, at that point in time, full. files that have been deleted but are still held on to by running processes do consume space. that space cannot be used for other files.
    – Mat
    Mar 19, 2011 at 9:02
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    df used space doesn't include the inode table. It includes data for files that don't have a name in any directory, like deleted files, special files like the ext4 journal, or files masked by another mounted file system.
    – Stéphane Chazelas
    Dec 15, 2017 at 11:26
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When du is larger than df, the usual reason is "sparse blocks": if a program doesn't actually write to a disk block but instead seeks past it, it gets a zero pointer in the inode's block allocation map and no actual disk space is reserved for it. If you later write to it, an actual disk block will be allocated and the map will be changed to point to the new block.

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    I don't think sparse blocks are counted in du.
    – Barmar
    Feb 2, 2015 at 18:54
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    FWIW, in Linux coreutils (as of 4.5.8, way long ago), there's an --apparent-size option which takes sparse blocks into account.
    – mattdm
    Jan 6, 2016 at 19:07

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