Content Addressable Data Synchronization Toolhttps://github.com/systemd/casync
casync provides a way to efficiently transfer files which change over
time over the Internet. It will split a given set into a git-inspired
content-addressable set of smaller compressed chunks, which can then
be conveniently transferred using HTTP. On the receiving side, these
chunks will be uncompressed and merged together to recreate the
original data. When the original data is modified, only the new chunks
have to be transferred during an update.