File-based backups, like
borgbackup, aren’t complete bare-metal backup solutions since before restoring files, the operating system needs to be installed, disk layout re-made, any encryption/luks re-created, etc. Plus the UUIDs probably won’t match on the restored system, so there might be more manual work to fix that.
Relax-and-Recover solves this problem, by creating a bootable recovery image specific to a system so that it can recreate the layout, partitions, encryption, etc and then optionally also integrate with one of many backup solutions to completely restore a system. The hardware might be identical, or with some effort could be changed.
rear is included in the default repositories of RedHat (Fedora), openSUSE, etc. It is recommended and even has an entire chapter in their documentation.
Quick article: https://access.redhat.com/solutions/2115051
Having said that, it seems to be “brittle” software that requires regular testing to be sure it actually works, and to make sure to know what to do manually in case it doesn’t.
rear is written (apparently extremely well) entirely in bash which has the benefit of having essentially no dependencies. An admin can read and modify individual scripts as needed. The downside is if anything goes unexpectedly, which is to be expected in a disaster, having deeper knowledge of
rear is probably required. It also depends on dozens of variables, and understanding what they are and their effects.
So, in the end, is it worth the effort, particularly for users of individual systems (as opposed to admins managing dozens or hundreds of systems)? Is anyone using