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怎样实现 MYSQL 主从搭建，针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。
一主单从
步骤：
1、配置 master 主机的 my.cnf，配置内容如下：
[mysqld]
user=mysql
pid-file=/var/run/mysqld/mysqld.pid
socket=/var/run/mysqld/mysqld.sock
port=3306
basedir=/usr
datadir=/var/lib/mysql
tmpdir=/tmp
log-bin=master-bin
log-bin-index=master-bin.index
server-id=1
配置完之后重启，使 my.cnf 生效
创建复制用户，并赋予 replication slave 权限给 slave 节点
mysql create user repl_user;
mysql grant replication slave on *.* to repl_user@mt identified by xyzzy;
2、配置 slave 从机的 my.cnf，配置内容如下：
[mysqld]
user=mysql
pid-file=/var/run/mysqld/mysqld.pid
socket=/var/run/mysqld/mysqld.sock
port=3306
basedir=/usr
datadir=/var/lib/mysql
tmpdir=/tmp
server-id=2
relay-log-index=slave-relay-bin.index
relay-log=slave-relay-bin
在 slave 上配置 slave 与 master 的连接
change master to
master_host= mo ,
master_port= 3306 ,
master_user repl_user ,
master_password= xyzzy ,
master_log_file= mysql-bin.00002 ,
master_log_pos=101;
启动 slave
start slave
3、查看 slave 的状态
mysql show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: mo
Master_User: repl_user
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master-bin.000001
Read_Master_Log_Pos: 946
Relay_Log_File: slave-relay-bin.000002
Relay_Log_Pos: 1092
Relay_Master_Log_File: master-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: 946
Relay_Log_Space: 1247
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)
如果 Slave_IO_Running、Slave_SQL_Running 均为 yes 则证明配置成功，如果有其中一个为 no，如下所示：
mysql show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Connecting to master
Master_Host: mo
Master_User: repl_user
Master_Port: 3306
Connect_Retry: 60
Master_Log_File:
Read_Master_Log_Pos: 4
Relay_Log_File: slave-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File:
Slave_IO_Running: No
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: 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 repl_user@mo:3306 – retry-time: 60 retries: 86400
Last_SQL_Errno: 0
Last_SQL_Error:
1 row in set (0.00 sec)
则查看 Last_IO_Errno、Last_IO_Error 参数，和 datadir 目录下的 hostname.err 文件找出错误日志信息，如下所示
[root@mt ~]# cd /var/lib/mysql/
[root@mt mysql]# ls
ibdata1 ib_logfile0 ib_logfile1 master.info mt.err mysql relay-log.info slave-relay-bin.000001 slave-relay-bin.index test
[root@mt mysql]# cd mt.err
-bash: cd: mt.err: Not a directory
[root@mt mysql]# tail -f n 200 mt.err
tail: cannot open `n for reading: No such file or directory
tail: cannot open `200 for reading: No such file or directory
== mt.err ==
160731 19:27:43 InnoDB: Initializing buffer pool, size = 8.0M
160731 19:27:43 InnoDB: Completed initialization of buffer pool
160731 19:27:43 InnoDB: Started; log sequence number 0 44233
160731 19:27:43 [Note] Event Scheduler: Loaded 0 events
160731 19:27:43 [Note] /usr/libexec/mysqld: ready for connections.
Version: 5.1.71 socket: /var/run/mysqld/mysqld.sock port: 3306 Source distribution
160731 19:47:02 [Note] CHANGE MASTER TO executed . Previous state master_host= , master_port= 3306 , master_log_file= , master_log_pos= 4 . New state master_host= mo , master_port= 3306 , master_log_file= , master_log_pos= 4 .
160731 19:47:09 [Note] Slave SQL thread initialized, starting replication in log FIRST at position 0, relay log ./slave-relay-bin.000001 position: 4
160731 19:47:09 [ERROR] Slave I/O: error connecting to master repl_user@mo:3306 – retry-time: 60 retries: 86400, Error_code: 2005
160731 21:13:09 [ERROR] Slave I/O: error connecting to master repl_user@mo:3306 – retry-time: 60 retries: 86400, Error_code: 2013
上述错误为 repl_user 没有给 slave 机 replication slave 权限
可以查看 select user,host,password from mysql.user; 看到 user 在哪个 host 上可以登陆，如果 repl_user 对应的 host 没有 slave 节点对应的主机名，则 repl_user 用户无法在 slave 机上进行远程连接到 master 所在的节点机。
可以使用 show binary logs 查看 logbin 的日志信息
可以使用 show master status \G 查看主节点信息
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