MySQL主从切换

1、查看从库数据库状态：
mysql> show processlist;
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
| Id | User        | Host            | db     | Command | Time  | State                                                                       | Info             |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
|  2 | root        | 127.0.0.1:59012 | sakila | Query   |     0 | NULL                                                                        | show processlist |
|  3 | system user |                 | NULL   | Connect | 17618 | Waiting for master to send event                                            | NULL             |
|  4 | system user |                 | NULL   | Connect | 17305 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL             |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
3 rows in set (0.00 sec)


mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.16.33.143
                  Master_User: master
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql.000003
          Read_Master_Log_Pos: 3296928
               Relay_Log_File: slave-relay-bin.000002
                Relay_Log_Pos: 3296845
        Relay_Master_Log_File: mysql.000003
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: 
          Replicate_Ignore_DB: test
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 3296928
              Relay_Log_Space: 3297001
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 1
1 row in set (0.00 sec)


mysql> show processlist;
+----+--------+---------------------+--------+-------------+-------+-----------------------------------------------------------------------+------------------+
| Id | User   | Host                | db     | Command     | Time  | State                                                                 | Info             |
+----+--------+---------------------+--------+-------------+-------+-----------------------------------------------------------------------+------------------+
|  1 | root   | 127.0.0.1:33623     | sakila | Query       |     0 | NULL                                                                  | show processlist |
|  2 | master | 172.16.33.144:48988 | NULL   | Binlog Dump | 17455 | Master has sent all binlog to slave; waiting for binlog to be updated | NULL             |
+----+--------+---------------------+--------+-------------+-------+-----------------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)


mysql> show master status;
+--------------+----------+--------------+------------------+
| File         | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+--------------+----------+--------------+------------------+
| mysql.000003 |  3296928 |              |                  |
+--------------+----------+--------------+------------------+
1 row in set (0.00 sec)


2、修改配置文件：
主库：read_only = 1
从库：#read_only = 1


3、操作从库：
mysql> show processlist;
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
| Id | User        | Host            | db     | Command | Time  | State                                                                       | Info             |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
|  2 | root        | 127.0.0.1:59012 | sakila | Query   |     0 | NULL                                                                        | show processlist |
|  3 | system user |                 | NULL   | Connect | 17770 | Waiting for master to send event                                            | NULL             |
|  4 | system user |                 | NULL   | Connect | 17457 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL             |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
3 rows in set (0.00 sec)


mysql> stop slave io_thread;
Query OK, 0 rows affected (0.00 sec)


mysql> show processlist;    
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
| Id | User        | Host            | db     | Command | Time  | State                                                                       | Info             |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
|  2 | root        | 127.0.0.1:59012 | sakila | Query   |     0 | NULL                                                                        | show processlist |
|  4 | system user |                 | NULL   | Connect | 17526 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL             |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)


确认从库的状态为：Slave has read all relay log


mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 172.16.33.143
                  Master_User: master
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql.000003
          Read_Master_Log_Pos: 3296928
               Relay_Log_File: slave-relay-bin.000002
                Relay_Log_Pos: 3296845
        Relay_Master_Log_File: mysql.000003
             Slave_IO_Running: No
            Slave_SQL_Running: Yes
              Replicate_Do_DB: 
          Replicate_Ignore_DB: test
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 3296928
              Relay_Log_Space: 3297001
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 1
1 row in set (0.00 sec)


4、查看主库状态：
mysql> show master status;
+--------------+----------+--------------+------------------+
| File         | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+--------------+----------+--------------+------------------+
| mysql.000003 |  3296928 |              |                  |
+--------------+----------+--------------+------------------+
1 row in set (0.00 sec)


5、主从切换，从库变主库：
mysql> slave stop;
Query OK, 0 rows affected, 1 warning (0.00 sec)


mysql> reset master;
Query OK, 0 rows affected (0.02 sec)


mysql> reset slave;
Query OK, 0 rows affected (0.00 sec)


mysql> show master status;
+--------------+----------+--------------+------------------+
| File         | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+--------------+----------+--------------+------------------+
| mysql.000001 |      107 |              |                  |
+--------------+----------+--------------+------------------+
1 row in set (0.00 sec)


6、主从切换，主库变从库：
mysql> reset master;
Query OK, 0 rows affected (0.02 sec)


mysql> reset slave;
Query OK, 0 rows affected (0.00 sec)


mysql> change master to master_host='172.16.33.144',master_port=3306,master_user='master',master_password='123456',master_log_file=' mysql-bin.000001',master_log_pos=107;
Query OK, 0 rows affected (0.04 sec)


7、重启主从：
[root@yoon ~]# service mysqld restart
Shutting down MySQL. SUCCESS! 
Starting MySQL.. SUCCESS! 


8、查看主从是否正常：
主库：
show processlist;
show master status;


从库：
show processlist;
start slave;
show slave status\G