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Asked: 2013-03-02 17:53:59 +0800 CST

same file different size in Linux and AIX

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we have file in Linux and copied to AIX. same file smaller size in AIX.

Linux - ext3 file system AIX - jfs2 file system

both file systems in same block size 4k

size in Linux
     du -sk p14727347_112030_AIX64-5L.zip
    1160568 p14727347_112030_AIX64-5L.zip
Size in AIX    
      du -sk p14727347_112030_AIX64-5L.zip
    1159484 p14727347_112030_AIX64-5L.zip

Any idea why its different

linux

1 Answers

  1. Best Answer

    Citing from my du(1) manual here (Fedora 18, coreutils-8.17-8.fc18):

    du - estimate file space usage

    There is a flag --apparent-size, that prints out (an approximation to) the space usage by the file, excluding extra space that the filesystem uses.

    So, du estimates the space on disk used by the file, i.e., data blocks and metadata. AIX and Linux presumably are using different filesystems, the space used by metadata doesn't have to be the same.

    Compare the output of ls -l for both files, that gives the length of the file itself.

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