I just browsed through the RSYNC paper, and if I understand it correctly, it does more than identify if a file has been changed... it tries to locate the change happen, so only the delta needs to be sent (like the unix "diff").

Wouldnt that be overkill for what we want here? we just want to ID if the file has changed, and if so, just overwrite the RIO file. That should be an easier checksum. Perhaps, even the same algorithm that is used now for checking for dups?

-Ted