MySQL ( MGR ) 08-(故障切换)

1.单主模式
1.1 模拟主节点挂掉（xag211）

[root@xag211 ~]# service mysqld stop

root@xag212:testdb [:15: ] 25 SQL->select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 2126c7e9-63c9-11eb-a1ba-000c299e2212 | xag212      |        3306 | ONLINE       |
| group_replication_applier | 2136c7e9-63c9-11eb-a1ba-000c299e2213 | xag213      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+


root@xag212:testdb [:22: ] 26 SQL->
SELECT ta.* ,tb.MEMBER_HOST,tb.MEMBER_PORT,tb.MEMBER_STATE FROM 
performance_schema.global_status ta,performance_schema.replication_group_members tb 
WHERE ta.VARIABLE_NAME='group_replication_primary_member' and ta.VARIABLE_VALUE=tb.MEMBER_ID;
+----------------------------------+--------------------------------------+-------------+-------------+--------------+
| VARIABLE_NAME                    | VARIABLE_VALUE                       | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+----------------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_primary_member | 2126c7e9-63c9-11eb-a1ba-000c299e2212 | xag212      |        3306 | ONLINE       |
+----------------------------------+--------------------------------------+-------------+-------------+--------------+

root@xag212:testdb [:22: ] 27 SQL->delete from t1 where Id=2;
Query OK, 1 row affected (0.00 sec)

1.2 原主节点故障修复（xag211）即启动

[root@xag211 ~]# service mysqld start

root@xag211:(none) [:26: ] 2 SQL->START GROUP_REPLICATION;

root@xag211:(none) [:26: ] 3 SQL->
select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 2116c7e9-63c9-11eb-a1ba-000c299e2211 | xag211      |        3306 | ONLINE       |
| group_replication_applier | 2126c7e9-63c9-11eb-a1ba-000c299e2212 | xag212      |        3306 | ONLINE       |
| group_replication_applier | 2136c7e9-63c9-11eb-a1ba-000c299e2213 | xag213      |        3306 | ONLINE       |
+---------------------------+--------------------------------------+-------------+-------------+--------------+

root@xag211:testdb [:27: ] 6 SQL->
select * from t1;
+----+----------+
| Id | TestName |
+----+----------+
|  1 | a        |
+----+----------+

2.要是三个节点都发生故障的话，在节点的故障都恢复后，需要手动重新做组复制，操作流程如下：

第一个节点
reset master;
SET SQL_LOG_BIN=1;
CHANGE MASTER TO MASTER_USER='repl', MASTER_PASSWORD='repl' FOR CHANNEL 'group_replication_recovery';
STOP GROUP_REPLICATION;
SET GLOBAL group_replication_bootstrap_group=ON;
START GROUP_REPLICATION;
SET GLOBAL group_replication_bootstrap_group=OFF;
SELECT * FROM performance_schema.replication_group_members;
  
第二个节点
reset master;
SET SQL_LOG_BIN=1;
CHANGE MASTER TO MASTER_USER='repl', MASTER_PASSWORD='repl' FOR CHANNEL 'group_replication_recovery';
START GROUP_REPLICATION;
  
第三个节点
reset master;
SET SQL_LOG_BIN=1;
CHANGE MASTER TO MASTER_USER='repl', MASTER_PASSWORD='repl' FOR CHANNEL 'group_replication_recovery';
START GROUP_REPLICATION;