Master-Master互为主备

1：按照主从配置步骤将MasterB配置成MasterA的从库；

2：确保MasterB没有写入，通过show master status命令在MasterB上得到其同步点，再将MasterA配置成MasterB的从库。

通常，为了简化逻辑，其中一个Master会设置为只读，正常只通过另外一个Master进行读写。 若要两边都写，为了避免自增id冲突，一般会设置奇偶错开，即一台的自增ID均为奇数，另一台均为偶数。

这里假设你已经按照我第一篇文章做了主从。

配置实例：

1：在Master B(Slave)的配置文件中添加

port = 3307

log_bin = /var/lib/mysql/mysql-binlog

binlog_do_db = testSM

2：在MasterA(Master)的配置文件中添加

prot=3306

master-host = 10.4.5.9

master-user = gechong1

master-password = gechong1

master-port = 3307

master-connect-retry = 5

replicate-do-db = testSM

3：在Master B(Slave)上创建复制账号gechong1

GRANT REPLICATION SLAVE ON *.* TO gechong1@'%' IDENTIFIED BY 'gechong1';

4：两边都重启服务登陆数据库

在Master A(Master)上查看

mysql> show master status;

+---------------------+----------+--------------+------------------+

| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |

+---------------------+----------+--------------+------------------+

| mysql-binlog.000002 | 106 | test | |

+---------------------+----------+--------------+------------------+

1 row in set (0.00 sec)

mysql> show slave status \G

*************************** 1. row ***************************

Slave_IO_State: Connecting to master

Master_Host: 10.4.5.9

Master_User: gechong1

Master_Port: 3306

Connect_Retry: 5

Master_Log_File:

Read_Master_Log_Pos: 4

Relay_Log_File: mysqld-relay-bin.000001

Relay_Log_Pos: 4

Relay_Master_Log_File:

Slave_IO_Running: No

Slave_SQL_Running: Yes

Replicate_Do_DB: test

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: 0

Relay_Log_Space: 106

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: 2013

Last_IO_Error: error connecting to master 'gechong1@10.4.5.9:3306' - retry-time: 5 retries: 86400

Last_SQL_Errno: 0

Last_SQL_Error:

1 row in set (0.00 sec)

在MasterB(Slave)上查看

mysql> show slave status \G

*************************** 1. row ***************************

Slave_IO_State: Waiting for master to send event

Master_Host: 10.4.14.168

Master_User: gechong

Master_Port: 3306

Connect_Retry: 5

Master_Log_File: mysql-binlog.000002

Read_Master_Log_Pos: 106

Relay_Log_File: mysqld-relay-bin.000006

Relay_Log_Pos: 254

Relay_Master_Log_File: mysql-binlog.000002

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

Replicate_Do_DB: test

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: 106

Relay_Log_Space: 558

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:

1 row in set (0.00 sec)

mysql> show master status;

+---------------------+----------+--------------+------------------+

| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |

+---------------------+----------+--------------+------------------+

| mysql-binlog.000001 | 327 | | |

+---------------------+----------+--------------+------------------+

1 row in set (0.00 sec)

可以看到 Master A：Slave_IO_Running: No

可以参照第一篇文档，重新配置参数即可。