emqttd@s1.emqtt.io 或emqttd@192.168.0.10    s1.emqtt.io 192.168.0.10
emqttd@s2.emqtt.io 或emqttd@192.168.0.20   s2.emqtt.io 192.168.0.20

-name emqttd@s1.emqtt.io

-name emqttd@192.168.0.10

$ ./bin/emqttd_ctl cluster join emqttd@s1.emqtt.io

Join the cluster successfully.Cluster status: [{running_nodes,['emqttd@s1.emqtt.io','emqttd@s2.emqtt.io']}]

$ ./bin/emqttd_ctl cluster join emqttd@s2.emqtt.ioJoin the cluster successfully.
Cluster status: [{running_nodes,['emqttd@s1.emqtt.io','emqttd@s2.emqtt.io']}]

$ ./bin/emqttd_ctl cluster statusCluster status: [{running_nodes,['emqttd@s1.emqtt.io','emqttd@s2.emqtt.io']}]

$ ./bin/emqttd_ctl cluster leave

$ ./bin/emqttd_ctl cluster remove emqttd@s2.emqtt.io

-export([status/1, broker/1, cluster/1, users/1, clients/1, sessions/1,routes/1, topics/1, subscriptions/1, plugins/1, bridges/1,listeners/1, vm/1, mnesia/1, trace/1]).
load() ->Cmds = [Fun || {Fun, _} <- ?MODULE:module_info(exports), is_cmd(Fun)],[emqttd_ctl:register_cmd(Cmd, {?MODULE, Cmd}, []) || Cmd <- Cmds].

%% @doc Join the mnesia cluster
-spec(join_cluster(node()) -> ok).
join_cluster(Node) when Node =/= node() ->%% Stop mnesia and delete schema firstensure_ok(ensure_stopped()),ensure_ok(delete_schema()),%% Start mnesia and cluster to nodeensure_ok(ensure_started()),ensure_ok(connect(Node)),ensure_ok(copy_schema(node())),%% Copy tablescopy_tables(),ensure_ok(wait_for(tables)).

%% @doc Cluster with node.
-spec(connect(node()) -> ok | {error, any()}).
connect(Node) ->case mnesia:change_config(extra_db_nodes, [Node]) of{ok, [Node]} -> ok;{ok, []}     -> {error, {failed_to_connect_node, Node}};Error        -> Errorend.%% @doc Copy schema.
copy_schema(Node) ->case mnesia:change_table_copy_type(schema, Node, disc_copies) of{atomic, ok} ->ok;{aborted, {already_exists, schema, Node, disc_copies}} ->ok;{aborted, Error} ->{error, Error}end.%% @doc Copy mnesia tables.
copy_tables() ->emqttd_boot:apply_module_attributes(copy_mnesia).

mnesia(copy) ->ok = emqttd_mnesia:copy_table(retained_message),ok = emqttd_mnesia:copy_table(backend_subscription).

-copy_mnesia({mnesia, [copy]}).mnesia(copy) ->ok = emqttd_mnesia:copy_table(route, ram_copies).

start(_StartType, _StartArgs) ->
print_banner(),
emqttd_mnesia:start(),

start() ->
ensure_ok(ensure_data_dir()),
ensure_ok(init_schema()),
ok = mnesia:start(),
init_tables(),
wait_for(tables).%% @doc Init mnesia schema or tables.
init_schema() ->
case mnesia:system_info(extra_db_nodes) of
[] -> mnesia:create_schema([node()]);
[_|_] -> ok
end.%% @private
%% @doc Init mnesia tables.
init_tables() ->
case mnesia:system_info(extra_db_nodes) of
[] -> create_tables();
[_|_] -> copy_tables()
end.

-boot_mnesia({mnesia, [boot]}).
-copy_mnesia({mnesia, [copy]}).%% Mnesia callbacks
%%--------------------------------------------------------------------mnesia(boot) ->
ok = emqttd_mnesia:create_table(retained_message, [
{type, ordered_set},
{disc_copies, [node()]},
{record_name, retained_message},
{attributes, record_info(fields, retained_message)},
{storage_properties, [{ets, [compressed]},
{dets, [{auto_save, 1000}]}]}]),
ok = emqttd_mnesia:create_table(backend_subscription, [
{type, bag},
{disc_copies, [node()]},
{record_name, mqtt_subscription},
{attributes, record_info(fields, mqtt_subscription)},
{storage_properties, [{ets, [compressed]},
{dets, [{auto_save, 5000}]}]}]);mnesia(copy) ->
ok = emqttd_mnesia:copy_table(retained_message),
ok = emqttd_mnesia:copy_table(backend_subscription).
4、数据库启动和拷贝的例子-module(emqttd_router).-boot_mnesia({mnesia, [boot]}).
-copy_mnesia({mnesia, [copy]}).mnesia(boot) ->
ok = emqttd_mnesia:create_table(route, [
{type, bag},
{ram_copies, [node()]},
{record_name, mqtt_route},
{attributes, record_info(fields, mqtt_route)}]);mnesia(copy) ->
ok = emqttd_mnesia:copy_table(route, ram_copies).

-boot_mnesia({mnesia, [boot]}).
-copy_mnesia({mnesia, [copy]}).mnesia(boot) ->ok = emqttd_mnesia:create_table(route, [{type, bag},{ram_copies, [node()]},{record_name, mqtt_route},{attributes, record_info(fields, mqtt_route)}]);mnesia(copy) ->ok = emqttd_mnesia:copy_table(route, ram_copies).