anchor.diff:          {ok, _Pid} when BackendDB == bitcask ->
               ok = bitcask:merge(Path),
               start_child_1(SupRef, InstanceName, NumOfDBProcs - 1,
  -                          BackendDB, DBRootPath, [Id|Acc]);
  +                          IsOneDevice, BackendDB, DBRootPath, [Id|Acc]);
           {ok, _Pid} ->
               start_child_1(SupRef, InstanceName, NumOfDBProcs - 1,
  -                          BackendDB, DBRootPath, [Id|Acc]);
  +                          IsOneDevice, BackendDB, DBRootPath, [Id|Acc]);
           Cause ->
               io:format("~w:~w - ~w ~p~n", [?MODULE, ?LINE, Id, Cause]),
               case ?MODULE:stop() of
  
positive.code:             true = ets:insert(?ETS_TABLE_NAME, {InstanceName, Acc})
      end,
      ok;
  start_child_1(SupRef, InstanceName, NumOfDBProcs, BackendDB, DBRootPath, Acc) ->
      BackendMod = backend_mod(BackendDB),
      {Id, StrDBNumber} =
          begin
              NewDBNumber =  integer_to_list(NumOfDBProcs),
              {list_to_atom(atom_to_list(InstanceName)
                            ++ "_"
                            ++  NewDBNumber), NewDBNumber}
          end,
  
      Path = DBRootPath ++ StrDBNumber,
  
negative.code: start_child(SupRef, InstanceName, NumOfDBProcs, BackendDB, DBRootPath) ->
      ok = leo_misc:init_env(),
      catch ets:new(?ETS_TABLE_NAME, [named_table, public, {read_concurrency, true}]),
      start_child_1(SupRef, InstanceName, NumOfDBProcs - 1, (NumOfDBProcs == 1),
                    BackendDB, DBRootPath, []).
  
  %% @private
  start_child_1(_, InstanceName, -1, _, _, _, Acc) ->
      case ets:lookup(?ETS_TABLE_NAME, InstanceName) of
          [] ->
              true = ets:insert(?ETS_TABLE_NAME, {InstanceName, Acc});
  