Rsnapshot is a powerfull rotating snapshot utility.
RSnapshot rotations processing use hardlinks ; only the changed files are copied, the rest is hard linked to the most recent backup. This method reduce hard disk used space.
Using remote root ssh access, Rsnapshot is able to backup a whole distant host. But, as you know, this is not an elegant nor a secure solution.
Consider we have several Remote Hosts, and a Backup Server host.