由于的我mgr建立在虚拟机上面（即使是正式环境，如果计划内的停机或者断电都需要关闭所有的节点），如何关闭所有的组成员，关闭的顺序还是比较重要的。

我的环境是一个primary，多个slave的架构，qht131为parmary,其它qht132,qht133,qht134为slave数据库。

1.关闭所有的组成员必须先先关闭slave，最后关闭master.

qht132,qht133,qht134：

[root@qht133 mysql]# service mysql stop
Shutting down MySQL..............                          [  OK  ]

qht131:

所有的slave关闭后都被移出了组成员：

mysql> select * from performance_schema.replication_group_members ;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e89b | qht131      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
1 row in set (0.00 sec)

最后也关闭primary数据库

[root@qht131 mysql]# service mysql stop
Shutting down MySQL..............                          [  OK  ]

2.开启组复制需要先开始primary，接着一个启动slave server.

[root@qht131 mysql]# service mysql start
Starting MySQL...........                                  [  OK  ]

由于group_replication_bootstrap_group参数 我们在配置文件中设为了OFF，所以需要手动打开设为ON.

mysql> show variables like 'group_replication_bootstrap_group';
+-----------------------------------+-------+
| Variable_name                     | Value |
+-----------------------------------+-------+
| group_replication_bootstrap_group | OFF   |
+-----------------------------------+-------+
1 row in set (0.24 sec)

mysql> set global group_replication_bootstrap_group=on;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from performance_schema.replication_group_members ;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e89b | qht131      |        3306 | OFFLINE      |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
1 row in set (0.02 sec)

在没有开启组复制之前member_state为OFFLINE

开启组复制之后记得将group_replication_bootstrap_group再设为off

mysql> start group_replication;
Query OK, 0 rows affected (2.12 sec)

mysql> set global group_replication_bootstrap_group=off;
Query OK, 0 rows affected (0.00 sec)

mysql>  select * from performance_schema.replication_group_members ;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e89b | qht131      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
1 rows in set (0.00 sec)

待primary server准备好后，其它的slave数据库可以一个个打开并开启组复制

qht132,qht133,qht134:

[root@qht132 mysql]# service mysql start
Starting MySQL.......                                      [  OK  ]
mysql> start group_replication;
Query OK, 0 rows affected (6.52 sec)

可能出现的问题：

mysql> start group_replication;
ERROR 3092 (HY000): The server is not configured properly to be an active member of the group. Please see more details on error log.

同时错误日志：

2018-05-17T03:08:40.654242Z 2 [ERROR] Plugin group_replication reported: '[GCS] The member is leaving a group without being on one.'
2018-05-17T03:08:40.654369Z 2 [Note] Plugin group_replication reported: 'auto_increment_increment is reset to 1'
2018-05-17T03:08:40.654378Z 2 [Note] Plugin group_replication reported: 'auto_increment_offset is reset to 1'
2018-05-17T03:08:40.654551Z 7 [Note] Error reading relay log event for channel 'group_replication_applier': slave SQL thread was killed

2018-05-17T03:08:40.657610Z 4 [Note] Plugin group_replication reported: 'The group replication applier thread was killed'

解决办法：检查一下primary server组复制的状态，group_replication_bootstrap_group是否为on，performance_schema.replication_group_members是否为ONLINE。

全部启动好后：

mysql> select * from performance_schema.replication_group_members ;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e89b | qht131      |        3306 | ONLINE       |
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e89c | qht134      |        3306 | ONLINE       |
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e90b | qht132      |        3306 | ONLINE       |
| group_replication_applier | bb0dea82-58ed-11e8-94e5-000c29e8e91b | qht133      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
4 rows in set (0.00 sec)