Porting a system from RedHat to Ubuntu yields smaller directories
 

Hello,

Has anyone ported a system from Red Hat to Ubuntu before? (or vice versa).

I have a system that I recently upgraded and made the switch from Red Hat 4 to Ubuntu 12.04. to move the files over from one system to the next I ran an rsync. The result was the same number of files but the size on the directory was smaller. Is this normal? Or is there a problem that I'm not seeing. I thought maybe the two systems either handle disk usage differently or maybe used a different character encoding...let me know if you've run into this. Thanks!

What does "du --apparent-size -s /some/path" return on both systems?

a wild guess
the difference in the file systems on the ancient rhel4 and the modern Ubuntu 12.04

what was being used on rhel4 ?
And what is currently being used on 12.04 ( LTS -- guessing) ?

A directory (that is, the directory file itself) never shrinks. Once it has grown to accommodate a large number of file names, that space is never released. When you make a copy of that directory, the new directory will be sized for the current number of files.

Old Box (Red Hat 4):

New Box (Ubuntu 12.04 LTS):

As you can see it's a very small difference, which is what makes me think that it has something to do with the differences between the way the file systems save files/directories.

on rhel4 it was ext3 and on ubuntu 12.04 it's ext4.

Interesting, I'm going to test this.

After playing around with it quick, it seems the directory size output from changes to reflect the contents so this is not the answer.

And I think you have found the answer. Different filesystems will use up different amounts of space for storing the same data.