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                                                             | showprocesslist |
|  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 toupdate it | NULL           |
+----+-------------+-----------------+--------+---------+-------+-----------------------------------------------------------------------------+------------------+
3 rows in set (0.00 sec)


mysql> show slave status\G
*************************** 1. row***************************
             Slave_IO_State: Waiting formaster 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 allbinlog 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                                                             | showprocesslist |
|  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 toupdate 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                                                             | showprocesslist |
|  4 | system user |              | NULL   | Connect | 17526 |Slave has read all relay log; waiting for the slave I/O thread toupdate 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 tomaster_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