The space used by hard-linked files will be included only in the first
directory where they are encountered. In your first case, linked files seen prior to the /51 directory would not have had their space included again under that directory. In the second case, _only_ the /51 directory is being examined, so all space will be included.
-- Bob Nichols "NOSPAM" is really part of my email address. Do NOT delete it.
Thank you, this makes sense. I was starting to worry that the filesystem is broken. I'll modify my rsync command to preserve hard links.
Radu