anchor.diff:  get(Bucket, Key, State) ->
       File = location(State, {Bucket, Key}),
       case filelib:is_file(File) of
  -        false -> {error, not_found, State};
  -        true -> {ok, element(2, file:read_file(File)), State}
  +        false ->
  +            {error, not_found, State};
  +        true ->
  +            {ok, Bin} = file:read_file(File),
  +            case unpack_ondisk(Bin) of
  +                bad_crc ->
  +                    %% TODO logging?
  +                    {error, not_found, State};
  +                Val ->
  +                    {ok, Val, State}
  +            end
       end.
   
   %% @spec atomic_write(File :: string(), Val :: binary()) ->
  
positive.code: -spec start(integer(), config()) -> {ok, state()} | {error, term()}.
  start(Partition, Config) ->
      PartitionName = integer_to_list(Partition),
      ConfigRoot = app_helper:get_prop_or_env(fs_backend_data_root, Config, riak_kv),
      if
          ConfigRoot =:= undefined ->
              riak:stop("fs_backend_data_root unset, failing");
  
negative.code: %%       normal path.
  atomic_write(File, Val) ->
      FakeFile = File ++ ".tmpwrite",
      case file:write_file(FakeFile, pack_ondisk(Val)) of
          ok ->
              file:rename(FakeFile, File);
          X -> X
  