Hopefully someone has seen this before. I'm trying to copy all directory contents from the source to a different directory, and for this I started using the Commons FileUtils.copyDirectorytoDirectory method(File src, File dest). The code is pretty simple:

```
public static void copyDirtoDir(String src, String dest) {
    File s = new File(src);
    File d = new File(dest);
    try {
        FileUtils.copyDirectoryToDirectory(s, d);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

```

To run this test on Linux, I'm running the app as a JAR and passing the src and dest strings from the command line. The problem is that when I check the resulting directory size after execution, there's a huge difference in size (with the copied dir around twice the size of the original - checked using 'du -sh').

I then simply tried with nio.FileChannels, as follows:

```
public static void copyFile(File in, File out) throws IOException {
    FileChannel source = new FileInputStream(in).getChannel();
    FileChannel destination = new FileOutputStream(out).getChannel();

        source.transferTo(0, source.size(), destination);

    source.close();
    destination.close();
}

```

Calling this method for every file inside the directory. The resulting size from this variation is also around twice the size of the original. If I do a listing of the directories' contents, they are the same.

Is there any missing parameter or something that could be causing this size difference?