I've just copied a dir tree to another disk with
cp -a. This tree is ~70GB big with millions of files, and diff was taking forever to finish, so I was looking for other methods to compare the dirs.
First I launched find on both the dirs and the result was the same.
After I launched du -h and one dir gave 72GB, the other 75. What can cause this difference supposing the copying process went well? Disk block size is the same, 4096. One partion is EXT3, the other EXT4, could be this?