I built a home backup server that works good enough for me:

* zfs for snapshots (and send my inc snapshots from my laptop) * zfs fs with snapshots to rsync non-zfs enabled devices (read: wife's mbp && imac) * rpi3 as brain (slow, but works) * 2x2Tb drives on a zraid

It took me a while to get it to where I wanted, but it was cheap (~230), low power and safe enough for home. I recently did a full reinstall from scratch and it took me less than 15 min to get my system back (I have my /home as a zfs fs backed up).