怎样实现MYSQL主从搭建

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_userrepl_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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