{lib, ...}: {
  fileSystems."/persist".neededForBoot = true;
  fileSystems."/nix".neededForBoot = true;
  boot.initrd.postDeviceCommands = lib.mkAfter ''
    mkdir /btrfs_tmp
    mount /dev/root_vg/root /btrfs_tmp
    if [[ -e /btrfs_tmp/root ]]; then
      mkdir -p /btrfs_tmp/old_roots
      timestamp=$(date --date="@$(stat -c %Y /btrfs_tmp/root)" "+%Y-%m-%-d_%H:%M:%S")
      mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
    fi

    delete_subvolume_recursively() {
      IFS=$'\n'
      for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
        delete_subvolume_recursively "/btrfs_tmp/$i"
      done
      btrfs subvolume delete "$1"
    }

    for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
      delete_subvolume_recursively "$i"
    done

    btrfs subvolume create /btrfs_tmp/root
    umount /btrfs_tmp
  '';
  environment.persistence."/persist" = {
    enable = true;
    hideMounts = true;
    directories = [
      "/var/log"
      "/var/lib/bluetooth"
      "/var/lib/nixos"
      "/var/lib/fprint"
      "/var/lib/systemd/coredump"
      "/etc/nixos"
      "/etc/NetworkManager"
    ];
    files = [
      "/etc/machine-id"
      "/etc/ssh/ssh_host_ed25519_key"
      "/etc/ssh/ssh_host_ed25519_key.pub"
      #"/var/lib/sops-nix/key.txt"
    ];
  };
}
