anchor.diff:      case rpc:call(Node, ?API_STORAGE, rebalance, [Info], ?DEF_TIMEOUT) of
           ok ->
               rebalance_5(T, Acc);
  -        {_, Cause}->
  -            ?error("rebalance_5/2", "node:~w, cause:~p", [Node, Cause]),
  -            rebalance_5(T, [{Node, Cause}|Acc]);
  -        timeout = Cause ->
  -            ?error("rebalance_5/2", "node:~w, cause:~p", [Node, Cause]),
  -            rebalance_5(T, [{Node, Cause}|Acc])
  +        Error ->
  +            %% @TODO enqueue a message (fail distribution of rebalance-info)
  +            Cause_1 = case Error of
  +                          {_, Cause} -> Cause;
  +                          timeout = Cause -> Cause
  +                      end,
  +            ?error("rebalance_5/2", "node:~w, cause:~p", [Node, Cause_1]),
  +            rebalance_5(T, [{Node, Cause_1}|Acc])
       end.
   
   
  
positive.code: %% @doc Do Rebalance which affect all storage-nodes in operation.
  %% [process flow]
  %%     1. Judge that "is exist attach-node OR detach-node" ?
  %%     2. Create RING (redundant-manager).
  %%     3. Distribute each storage node. (from manager to storages)
  %%     4. Confirm callback.
  %%
  -spec(rebalance() ->
               ok | {error, any()}).
  
negative.code: 
  
  %% @private
  rebalance_5([], []) ->
      ok;
  rebalance_5([], Acc) ->
  