anchor.diff:      logplex_shard_info:copy(?NEW_READ_MAP, ?CURRENT_READ_MAP),
       ok.
   
  -new_shard_info({one_for_one, OldNewMap}) ->
  -    {RM, RI, _} = logplex_shard_info:read(?CURRENT_READ_MAP),
  -    NewReadMap = dict:map(fun (_Slice, {OldUrl, _OldPid}) ->
  -                                  NewUrl = proplists:get_value(OldUrl, OldNewMap),
  -                                  NewPid = add_pool(NewUrl),
  -                                  {NewUrl, NewPid}
  -                          end,
  -                          RM),
  -    {WM, WI, _} = logplex_shard_info:read(?CURRENT_WRITE_MAP),
  -    NewWriteMap = dict:map(fun (_Slice, {OldUrl, _OldPid}) ->
  -                                   NewUrl = proplists:get_value(OldUrl, OldNewMap),
  -                                   NewPid = add_buffer(NewUrl),
  -                                   {NewUrl, NewPid}
  -                           end,
  -                           WM),
  -    logplex_shard_info:save(?NEW_READ_MAP,
  -                            NewReadMap, RI),
  -    logplex_shard_info:save(?NEW_WRITE_MAP,
  -                            NewWriteMap, WI),
  -    ok;
   new_shard_info({replacements, NewUrls}) ->
       populate_info_table(?NEW_READ_MAP, ?NEW_WRITE_MAP,
                           NewUrls),
  
positive.code: %% If anything goes wrong:
  %%   abort_url_update(Cluster).
  
  prepare_new_urls({one_for_one, NewIps}) ->
      NewIpsSorted = lists:sort(NewIps),
      OldUrls = lists:sort([binary_to_list(Url)
                            || Url <- urls()]),
      length(OldUrls) =:= length(NewIpsSorted)
          orelse erlang:error({invalid_ip_list, different_length_to_existing}),
      NewUrls = [ update_redis_host(OldUrl, NewIp)
                  || {OldUrl, NewIp} <- lists:zip(OldUrls, NewIpsSorted)],
      {one_for_one, lists:zip(OldUrls, NewUrls)};
  prepare_new_urls({replacements, NewUrls}) ->
      {replacements, NewUrls}.
  
  
negative.code:     end;
  parse_redis_uri_db(_) -> [].
  
  redis_sort(Urls) ->
      Parsed = lists:map(fun parse_redis_uri/1, Urls),
      [ proplists:get_value(url, Server)
  