du - different results when comparing macOS and Linux directories

[gebseng]

Hi everyone,

I have two supposedly identical directories on macOS (HFS+) and Ubuntu Server 20.04 (EXT4). I copied the directory from the Mac to the Linux machine using

rsync -auv [directory1] user@192.168.0.20:[directory2] 

without problems. Now I have some problems with differing sizes of those two directories. Lets start with this:

On the Linux machine, when my path is inside [directory2], I do

ls | wc -l

, I get

147296

as a result for the number of files in the directory

du -shk

, I get

146460120

as a result in kB

On the Mac, inside [directory1], I do the same

ls | wc -l

, I get

147296

as a result for the number of files in the directory

du -shk

, I get

149033768

as a result in kB

To explain the size difference, on the Linux machine I tried

du -shk --exclude './.*'

to exclude hidden files and resource files, I get

146445092

as a result in kB

same on the Mac:

du -shk -I './.*'

to exclude hidden files and resource files, I get

149033768

as a result in kB, same as before

When I do a

diff -x '.*' -rq [dir1] [dir2]

it ends without output, so seemingly the same.

What could explain the size differences? Or is there a better way to compare file sizes?

[dinkidonk]

The difference may be related to a difference in size of file system entries and extra space allocated for sparse files. Try command "du -sb" to get the apparent byte size instead of a block size.

[gebseng]

Thanks! on the Ubuntu machine,

du -sb

gives an output of 149672510341.

On the Mac, I get a

du: illegal option -- b

error. The macOS -du manpage states

-h "Human-readable" output. Use unit suffixes: Byte, Kilobyte, Megabyte, Gigabyte, Terabyte and Petabyte.

, but I'm not sure how to use this.

[The Cog]

Try this instead of -b then:

du -s --apparent-size

[kneutron]

--Mac HFS+ does not support sparse files. As long as the number of files are the same, and they pass a basic md5sum / sha1sum check, it could be the difference between 512 sector size and 4096 on the different drives. And HFS+ just stores files a little differently.

REF:
https://en.wikipedia.org/wiki/HFS_Plus