

But if a different tools fits better here, I am able to switch. This way the rsync client would send only a few bytes for a huge directory tree.

Is there a way to tell rsync to make a hash-sum of a sub directory tree? Since the network is slow I would like to avoid to send 80k times information about each file. I guess that the rsync clients sends data for each of the 80k files. These huge directory trees contain a lot of small files (about 80k files).

It takes up to five minutes for rsync to detect, that nothing has changed in huge directories. Unfortunately the network to some servers is slow.
