How does rsync work? Is this a trick enough not to transfer anything if your files are no different?

Question

Nothing to add to the question. How does rsync filter the data that it must transfer and which it can leave separately?

Answer 1

Directly from the man page ( http://linux.die.net/man/1/rsync ):

"Rsync finds files that need to be transferred using the lqquick checkrq algorithm (default), which searches for files that have been resized or recently. Any changes to other saved attributes (at the request of options) are created in the destination file directly when a quick check indicates that the file data does not need to be updated. "