I am looking to do some backups to S3 and want to reduce the bandwidth as much as possible. I am looking at a few options. It seems like librsync is the best solution for low bandwidth remote backups.
I've been reading on how librsync works. And it seems like the remote end needs to calculate the checksum on the blocks of the files it is comparing (as well as the local end). I would assume that S3 can't do those checksum calculations since it only serves files.
I've also read that S3 doesn't support separating files into chunks. It can only offer the whole file or nothing.
If both (or either) of these statements are true, would librsync be essentially useless? Can someone shed some light on this for me?