anchor.diff:                                };
                               }) snapshotNames);
       })
  +
  +    (mkIf enableAutoScrub {
  +      systemd.services.zfs-scrub = {
  +        description = "ZFS pools scrubbing";
  +        after = [ "zfs-import.target" ];
  +        serviceConfig = {
  +          Type = "oneshot";
  +        };
  +        script = ''
  +          ${packages.zfsUser}/bin/zpool scrub ${
  +            if cfgScrub.pools != [] then
  +              (concatStringsSep " " cfgScrub.pools)
  +            else
  +              "$(${packages.zfsUser}/bin/zpool list -H -o name)"
  +            }
  +        '';
  +      };
  +
  +      systemd.timers.zfs-scrub = {
  +        wantedBy = [ "timers.target" ];
  +        timerConfig = {
  +          OnCalendar = cfgScrub.interval;
  +          Persistent = "yes";
  +        };
  +      };
  +    })
     ];
   }
  
positive.code:         zfsSupport = true;
        };
  
        environment.etc."zfs/zed.d".source = "${packages.zfsUser}/etc/zfs/zed.d/*";
  
        system.fsPackages = [ packages.zfsUser ]; # XXX: needed? zfs doesn't have (need) a fsck
        environment.systemPackages = [ packages.zfsUser ]
  
negative.code:         type = types.int;
          description = ''
            Number of monthly auto-snapshots that you wish to keep.
          '';
        };
      };
  
      services.zfs.autoScrub = {
        enable = mkOption {
          default = false;
          type = types.bool;
          description = ''
            Enables periodic scrubbing of ZFS pools.
          '';
        };
  
        interval = mkOption {
          default = "Sun, 02:00";
          type = types.str;
          example = "daily";
          description = ''
            Systemd calendar expression when to scrub ZFS pools. See
            <citerefentry><refentrytitle>systemd.time</refentrytitle>
            <manvolnum>5</manvolnum></citerefentry>.
          '';
        };
  
        pools = mkOption {
          default = [];
          type = types.listOf types.str;
          example = [ "tank" ];
          description = ''
            List of ZFS pools to periodically scrub. If empty, all pools
            will be scrubbed.
          '';
        };
      };
  