mysql5.7 主从复制的正常切换【转】

目前环境如下：

master server IP:172.17.61.131

slave server IP:172.17.61.132

mysql version: mysql-5.7.21-linux

目标：计划内的主从复制正常切换

1.切换之前需要检查slave的同步状态，对master进行锁表。

slave server: 确保Slave_IO_Running和Slave_SQL_Running都为YES

mysql> show slave status G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.61.131
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql_bin.000036
          Read_Master_Log_Pos: 154
               Relay_Log_File: slave_relay_bin.000003
                Relay_Log_Pos: 367
        Relay_Master_Log_File: mysql_bin.000036
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
             ...
1 row in set (0.00 sec)

master server进行锁表操作，由于我是测试环境没有应用，所以锁表很快。

2.在flush tables with read lock成功获得锁之前，必须等待所有语句执行完成（包括SELECT）。所以如果有个慢查询在执行，或者一个打开的事务，或者其他进程拿着表锁，flush tables with read lock就会被阻塞，直到所有的锁被释放。

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.01 sec)

3.接着要确保master所有的binlog已同步到slave，并且slave都已apply了所有的binlog。

maser server:

mysql> show processlist;
+----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
| Id | User | Host                | db   | Command     | Time | State                                                         | Info             |
+----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
|  2 | repl | 172.17.61.132:60079 | NULL | Binlog Dump | 1907 | Master has sent all binlog to slave; waiting for more updates | NULL             |
|  3 | root | localhost           | NULL | Query       |    0 | starting                                                      | show processlist |
+----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)

slave server:

mysql> show processlist;
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
| Id | User        | Host      | db   | Command | Time | State                                                  | Info             |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
|  1 | system user |           | NULL | Connect | 1918 | Slave has read all relay log; waiting for more updates | NULL             |
|  2 | system user |           | NULL | Connect | 1918 | Waiting for master to send event                       | NULL             |
|  4 | root        | localhost | NULL | Query   |    0 | starting                                               | show processlist |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
3 rows in set (0.00 sec)

4.停止slave的进程 

slave sever:

mysql> STOP SLAVE IO_THREAD;
Query OK, 0 rows affected (0.02 sec)

mysql>  show processlist;
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
| Id | User        | Host      | db   | Command | Time | State                                                  | Info             |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
|  1 | system user |           | NULL | Connect | 2039 | Slave has read all relay log; waiting for more updates | NULL             |
|  4 | root        | localhost | NULL | Query   |    0 | starting                                               | show processlist |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
2 rows in set (0.00 sec)

5.修改slave的my.cnf，重启mysql

[mysqld]
socket = /usr/local/mysql/mysql.sock
character_set_server= utf8
init_connect= 'SET NAMES utf8'
basedir= /usr/local/mysql
datadir= /u01/mysql
socket = /u01/mysql/mysql.sock
log-error= /u01/log/mysql/mysql_3306.err
pid-file= /u01/mysql/mysqld.pid
lower_case_table_names = 1
sql_mode= STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
secure-file-priv = /u01/backup
server-id=10001
log_bin = /u01/mysql/mysql_bin
#skip-grant-tables
innodb_flush_log_at_trx_commit=1
sync_binlog=1
#relay-log=/u01/mysql/slave_relay_bin
expire_logs_days=10
read_only=0
#relay_log_recovery=on
#relay_log_info_repository=TABLE
max_binlog_size=1073741824
#autocommit=off
#long_query_time=15
#slow_query_log=on

[root@qht132 ~]# service mysql restart
Shutting down MySQL..                                      [  OK  ]
Starting MySQL.                                            [  OK  ]

需要开启原slave的bin_log,关闭relay_log*，关闭read_only

5.提升slave为master

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

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

mysql> reset slave all;
Query OK, 0 rows affected (0.01 sec)

mysql> show variables like 'read_only';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | OFF   |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show master status G
*************************** 1. row ***************************
             File: mysql_bin.000001
         Position: 154
     Binlog_Do_DB:
 Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)

在新的master上建立同步帐户并赋予同步权限（由于我为了省事，之前主从配置的时候将61网段的权限都赋予给了repl，所以这一步我也可以不做）

mysql> grant replication slave on *.* to 'repl'@'172.17.61.%';
Query OK, 0 rows affected (0.01 sec)

6.修改原master的my.cnf，重启mysql

[mysqld]
socket = /usr/local/mysql/mysql.sock
character_set_server= utf8
init_connect= 'SET NAMES utf8'
basedir= /usr/local/mysql
datadir= /u01/mysql
socket = /u01/mysql/mysql.sock
log-error= /u01/log/mysql/mysql_3306.err
pid-file= /u01/mysql/mysqld.pid
lower_case_table_names = 1
sql_mode= STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
secure-file-priv = /u01/backup
server-id=10000
#log_bin = /u01/mysql/mysql_bin
#skip-grant-tables
#innodb_flush_log_at_trx_commit=1
#sync_binlog=1
expire_logs_days=10
read_only=1
relay_log_recovery=on
relay_log_info_repository=TABLE
#max_binlog_size=1073741824
#autocommit=off
#long_query_time=15
#slow_query_log=on

关闭原master的binlog，开启relay_log*，打开read_only状态

[root@qht131 ~]# service mysql restart
Shutting down MySQL..                                      [  OK  ]
Starting MySQL.                                            [  OK  ]

7.将master切换为slave

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

mysql> change master to
    -> master_host='172.17.61.132',
    ->  master_user='repl',
    ->  master_password='repl',
    -> master_log_file='mysql_bin.000001',
    -> master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.03 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

master_log_file和master_log_pos需指定为新master切换后显示的起始位置

检查一下新slave的状态，确保slave_io_running和slave_sql_running都为YES。

mysql> show slave statusG
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.61.132
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql_bin.000001
          Read_Master_Log_Pos: 360
               Relay_Log_File: qht131-relay-bin.000002
                Relay_Log_Pos: 526
        Relay_Master_Log_File: mysql_bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB:
           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: 360
              Relay_Log_Space: 734
              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: 10001
                  Master_UUID: 744cfcde-3a9b-11e8-b299-000c2900d025
             Master_Info_File: /u01/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind:
      Last_IO_Error_Timestamp:
     Last_SQL_Error_Timestamp:
               Master_SSL_Crl:
           Master_SSL_Crlpath:
           Retrieved_Gtid_Set:
            Executed_Gtid_Set:
                Auto_Position: 0
         Replicate_Rewrite_DB:
                 Channel_Name:
           Master_TLS_Version:
1 row in set (0.00 sec)

8.最后进行测试

新master:

mysql> create table t3 ( c1 int);
Query OK, 0 rows affected (0.05 sec)

新slave:

mysql> use l5m
Database changed
mysql> show tables;
+---------------+
| Tables_in_l5m |
+---------------+
| t1            |
| t2            |
| t3            |
| test_emp      |
| tt            |
+---------------+
5 rows in set (0.00 sec)

mysql> show create table t3G
*************************** 1. row ***************************
       Table: t3
Create Table: CREATE TABLE `t3` (
  `c1` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

至此测试完毕！

转自

mysql5.7 主从复制的正常切换 - CSDN博客

https://blog.csdn.net/jolly10/article/details/79877564