Another backup possibility I currently use: ZFS on a backup server (not necessarily ZFS on the system that should be backed up), pull data with rsync on the backup host to a ZFS, after that make a snapshot for an "incremental backup".

So simplified it's like: rsync -avx remote:/etc /backup/ && zfs snapshot backup@`date`

With zfSnap (https://github.com/graudeejs/zfSnap) you can tell how long incremental backups/snapshots are kept, "rsync && zfSnap -d -a 1w backup"

You can take advantage of the /backup/.zfs/snapshot directory to access all snapshots, built-in compression and possible data deduplication.

If you also have ZFS on the remote host, you can use zfs send and zfs receive to transfer the snapshot directly to the backup server, instead of using rsync for the diff.