MHA实现mysql主从数据库手动切换的方法

本文实例讲述了MHA实现mysql主从数据库手动切换的方法，分享给大家供大家参考。具体方法如下：

一、准备工作

1、分别在Master和Slave执行如下,方便mha检查复制:

grant all privileges on *.* to 'root'@'10.1.1.231' identified by 'rootpass';
grant all privileges on *.* to 'root'@'10.1.1.234' identified by 'rootpass';
grant replication slave on *.* to 'jpsync'@'10.1.1.231' identified by 'jppasswd';
grant replication slave on *.* to 'jpsync'@'10.1.1.234' identified by 'jppasswd';
flush privileges;

2、将master设置为只读
 

mysql> set global read_only=1;
Query OK, 0 rows affected (0.00 sec)
mysql> show variables like 'read_only';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | ON    |
+---------------+-------+
1 row in set (0.00 sec)

交互模式:

#masterha_master_switch --master_state=alive --conf=/etc/masterha/app1.cnf    --new_master_host=10.1.1.231  --new_master_port=63306

或非交互模式:

#masterha_master_switch --master_state=alive --conf=/etc/masterha/app1.cnf    --new_master_host=10.1.1.231  --new_master_port=63306 —interactive=0

二、切换完以后，如何让10.1.1.231为主，10.1.1.234为从，操作步骤:

1、主上执行:

mysql> show master status;
+-------------------------+----------+--------------+--------------------------------------+-------------------+
| File                    | Position | Binlog_Do_DB | Binlog_Ignore_DB                     | Executed_Gtid_Set |
+-------------------------+----------+--------------+--------------------------------------+-------------------+
| mysql-master-bin.000013 |      120 | denovo_ng    | mysql,denovo,test,information_schema |                   |
+-------------------------+----------+--------------+--------------------------------------+-------------------+
1 row in set (0.00 sec)

2、在10.1.1.234上执行如下sql命令；

change master to master_host='10.1.1.231',master_port=63306,master_user='jpsync',
master_password='jppasswd', master_log_file='mysql-master-bin.000013',master_log_pos=120;
 
mysql> show slave status＼G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.1.1.231
                  Master_User: jpsync
                  Master_Port: 63306
                Connect_Retry: 60
              Master_Log_File: mysql-master-bin.000013
          Read_Master_Log_Pos: 120
               Relay_Log_File: compute-0-52-relay-bin.000002
                Relay_Log_Pos: 290
        Relay_Master_Log_File: mysql-master-bin.000013
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

3、查看master状态，并测试

mysql> show slave hosts;
+-----------+------+-------+-----------+--------------------------------------+
| Server_id | Host | Port  | Master_id | Slave_UUID                           |
+-----------+------+-------+-----------+--------------------------------------+
|      1052 |      | 63306 |      1025 | e25a3e4a-39c0-11e4-80cb-00259086c4b6 |
+-----------+------+-------+-----------+--------------------------------------+
1 row in set (0.00 sec)

主库10.1.1.231上插入记录

mysql> insert into  test_slave_002 values(555551111,1,55555,99999,44.11,2222,91919);
Query OK, 1 row affected (0.00 sec)

从库查询记录已经存在

mysql> select * from test_slave_002 where id=555551111;
+-----------+-----+-----------+--------------+----------+----------------+--------------+
| id        | tag | ticket_id | candidate_id | duration | source_file_id | source_start |
+-----------+-----+-----------+--------------+----------+----------------+--------------+
| 555551111 |   1 |     55555 |        99999 |    44.11 |           2222 |        91919 |
+-----------+-----+-----------+--------------+----------+----------------+--------------+
1 row in set (0.00 sec)

4、更新配置文件:
更新主库my.cnf配置添加

skip_slave_start

注意:防止重启数据库，启动slave进程，导致数据不一致。
更新从库my.cnf配置添加，设置slave库为只读:

read_only=1
relay_log_purge=0

然后重启主库和从库,观察库的信息:
主库信息:

mysql> show processlist;
+----+--------+------------------+------+-------------+------+-----------------------------------------------------------------------+------------------+
| Id | User   | Host             | db   | Command     | Time | State                                                                 | Info             |
+----+--------+------------------+------+-------------+------+-----------------------------------------------------------------------+------------------+
|  1 | jpsync | 10.1.1.234:49085 | NULL | Binlog Dump |   17 | Master has sent all binlog to slave; waiting for binlog to be updated | NULL             |
|  2 | root   | localhost        | NULL | Query       |    0 | init                                                                  | show processlist |
+----+--------+------------------+------+-------------+------+-----------------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)
 
mysql> show master status;
+-------------------------+----------+--------------+--------------------------------------+-------------------+
| File                    | Position | Binlog_Do_DB | Binlog_Ignore_DB                     | Executed_Gtid_Set |
+-------------------------+----------+--------------+--------------------------------------+-------------------+
| mysql-master-bin.000014 |      120 | denovo_ng    | mysql,denovo,test,information_schema |                   |
+-------------------------+----------+--------------+--------------------------------------+-------------------+
1 row in set (0.00 sec)

从库信息:

mysql> show slave status＼G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.1.1.231
                  Master_User: jpsync
                  Master_Port: 63306
                Connect_Retry: 60
              Master_Log_File: mysql-master-bin.000014
          Read_Master_Log_Pos: 120
               Relay_Log_File: compute-0-52-relay-bin.000005
                Relay_Log_Pos: 290
        Relay_Master_Log_File: mysql-master-bin.000014
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
 
mysql> show processlist;
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------------+------------------+
| Id | User        | Host      | db   | Command | Time | State                                                                       | Info             |
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------------+------------------+
|  1 | system user |           | NULL | Connect |   58 | Waiting for master to send event                                            | NULL             |
|  2 | system user |           | NULL | Connect |   58 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL             |
|  3 | root        | localhost | NULL | Query   |    0 | init                                                                        | show processlist |
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------------+------------------+
3 rows in set (0.00 sec)

希望本文所述对大家的MySQL数据库程序设计有所帮助。