I use bontmia since forever, based on the same rsync feature (link-dest for creating hard links to the unmodified files since the last backup). It also supports

I use bontmia since forever, based on the same rsync feature (link-dest for creating hard links to the unmodified files since the last backup). It also supports backup rotation and I think it's quite solid/reliable after all these years: https://github.com/hcartiaux/bontmia https://github.com/hcartiaux/bontmia