Sure you could, like Solaris did IIRC, zfs snapshot before updates was applied. What I mean is that a fs snapshot is ”dumb” in and of it self. If you couple z

Sure you could, like Solaris did IIRC, zfs snapshot before updates was applied. What I mean is that a fs snapshot is ”dumb” in and of it self. If you couple zfs with the nixos rebuild command, then… sure, I guess - but the previous generations are already more or less directly available, unless GC’d. This is what the fine manual has to say: Since Nix is good at being Nix, most users will want their server's data backed up, and don't mind reinstalling NixOS and then restoring data.