centos7 mariadb主从复制配置搭建详解步骤

Z时代
2024-01-10
分类：综合

花了小一天的时间，终于实现了centos7 mariadb主从复制配置搭建，下面记录一下过程

环境:

虚拟机:vm8; centos7 版本：7.2.1511; mariadb 版本：centos7.2内置的

主库服务器： 10.69.5.200，CentOS 7，MariaDB 10已安装，有数据。

从库服务器1： 10.69.5.201，CentOS 7，MariaDB 10已安装，无应用数据。

主服务器配置

以下操作在主服务器192.168.71.151的/etc/my.cnf上进行。

1.修改配置文件，命令：vim /etc/my.cnf，输入下列代码：

[root@localhost ~]# cat /etc/my.cnf

[mysqld]

datadir=/var/lib/mysql

socket=/var/lib/mysql/mysql.sock

`# 新添加的部分

# 配置主从时需要添加以下信息 start

innodb_file_per_table=NO

log-bin=/var/lib/mysql/master-bin #log-bin没指定存储目录，则是默认datadir指向的目录

binlog_format=mixed

server-id=200

#每个服务器都需要添加server_id配置，各个服务器的server_id需要保证唯一性，实践中通常设置为服务器IP地址的最后一位

#配置主从时需要添加以下信息 end

# Disabling symbolic-links is recommended to prevent assorted security risks

symbolic-links=0

# Settings user and group are ignored when systemd is used.

# If you need to run mysqld under a different user or group,

# customize your systemd unit file for mariadb according to the

# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]

log-error=/var/log/mariadb/mariadb.log

pid-file=/var/run/mariadb/mariadb.pid

# include all files from the config directory

!includedir /etc/my.cnf.d

最后，:wq!保存退出

2.重启mariadb服务，输入命令


[root@localhost ~]# systemctl restart mariadb.service

3.登录mariadb


[root@localhost ~]# mysql -u root -padmin

注：-p后是密码，中间没有空格

4.创建帐号并赋予replication的权限

从库,从主库复制数据时需要使用这个帐号进行


MariaDB [(none)]> GRANT REPLICATION SLAVE ON *.* TO 'root'@'10.69.5.%' IDENTIFIED BY 'admin';
Query OK, 0 rows affected (0.00 sec)

5.备份数据库数据，用于导入到从数据库中

加锁

实际工作中，备份的时候是不让往库中写数据的，所以数据库要加锁，只能读


MariaDB [(none)]> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.00 sec)

记录主库log文件及其当前位置


MariaDB [(none)]> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File       | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000001 |   694 |       |         |
+------------------+----------+--------------+------------------+

记住File和Position的部分，从服务器会用到

备份数据，输入命令：


[root@localhost ~]# mysqldump -uroot -p --all-databases > /root/db.sql

解锁主库

数据备份完成后，就可以释放主库上的锁：


MariaDB [(none)]> UNLOCK TABLES;
Query OK, 0 rows affected (0.00 sec)

从服务器配置

以下在从服务器上的操作

1.导入主库的数据


[root@localhost ~]# mysql -uroot -p < db.sql

2.从服务器/etc/my.cnf配置,设置relay-log

my.cnf文件中添加一行relay_log=relay-bin

如果不设置，默认是按主机名 + “-relay-bin”生成relay log。

[root@localhost ~]# cat /etc/my.cnf

[mysqld]

datadir=/var/lib/mysql

socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks

symbolic-links=0

`#配置主从时需要添加以下信息 start

innodb_file_per_table=NO

server-id=201 #一般与服务器ip的最后数字一致

relay-log=/var/lib/mysql/relay-bin

#配置主从时需要添加以下信息 end

# Settings user and group are ignored when systemd is used.

# If you need to run mysqld under a different user or group,

# customize your systemd unit file for mariadb according to the

# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]

log-error=/var/log/mariadb/mariadb.log

pid-file=/var/run/mariadb/mariadb.pid

# include all files from the config directory

!includedir /etc/my.cnf.d

3.重启服务


[root@localhost ~]# systemctl restart mariadb.service

4.登录mariadb


[root@localhost ~]# mysql -u root -padmin

5.设置主从复制


MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='10.69.5.200',MASTER_USER='root', MASTER_PASSWORD='admin', MASTER_LOG_FILE='master-bin.000001', MASTER_LOG_POS= 694;
Query OK, 0 rows affected (0.02 sec)

这个命令完成以下几个任务：

a.设置当前服务器为主服务器(10.69.5.200)的从库

b.提供当前数据库(从库)从主库复制数据时所需的用户名和密码，即上面的GRANT REPLICATION SLAVE ON *.* TO 'root'@'10.69.5.%' IDENTIFIED BY 'admin';设置的

c.指定从库开始复制主库时需要使用的日志文件和文件位置，即上面主库执行SHOW MASTER STATUS;显示结果中的File和Position

6.开启主从复制


MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.00 sec)

7.查看从库状态

MariaDB [(none)]> show slave status\G

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

Slave_IO_State: Waiting for master to send event

Master_Host: 10.69.5.200

Master_User: root

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: master-bin.000001

Read_Master_Log_Pos: 694

Relay_Log_File: relay-bin.000003

Relay_Log_Pos: 530

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: 694

Relay_Log_Space: 818

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: 200

1 row in set (0.00 sec)

注意：结果中Slave_IO_Running和Slave_SQL_Running必须为Yes，如果不是，需要根据提示的错误修改。

验证

主服务器：


MariaDB [(none)]> show databases;
+--------------------+
| Database      |
+--------------------+
| information_schema |
| mysql       |
| mytest       |
| performance_schema |
| test        |
+--------------------+
5 rows in set (0.04 sec)
MariaDB [(none)]> use mytest;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
MariaDB [mytest]> select * from user;
+----+------+
| id | name |
+----+------+
| 1 | t  |
| 2 | t2  |
| 3 | t3  |
+----+------+
3 rows in set (0.00 sec)
MariaDB [mytest]> insert into user(name) values('t4');
Query OK, 1 row affected (0.01 sec)
MariaDB [mytest]> select * from user;
+----+------+
| id | name |
+----+------+
| 1 | t  |
| 2 | t2  |
| 3 | t3  |
| 4 | t4  |
+----+------+
4 rows in set (0.00 sec)

查看从服务器数据是否变化：


MariaDB [(none)]> use mytest;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
MariaDB [mytest]> select * from user;
+----+------+
| id | name |
+----+------+
| 1 | t  |
| 2 | t2  |
+----+------+
2 rows in set (0.00 sec)
MariaDB [mytest]> select * from user;
+----+------+
| id | name |
+----+------+
| 1 | t  |
| 2 | t2  |
| 4 | t4  |
+----+------+
3 rows in set (0.00 sec)

可以看到，从服务器更新了数据

搭建过程中遇到的问题及解决方法

问题1：从服务器设置主从复制出现错误:


MariaDB [mytest]> start slave;
ERROR 1201 (HY000): Could not initialize master info structure; more error messages can be found in the MariaDB error log

发现

Slave_IO_Running: No

Slave_SQL_Running: No

进一步发现我输入的是：CHANGE MASTER TO MASTER_HOST='192.168.71.151',MASTER_USER='slave_user', MASTER_PASSWORD='bigs3cret', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS= 469;

重新输入：MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='10.69.5.200',MASTER_USER='root', MASTER_PASSWORD='admin', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS= 469;

报错：ERROR 1201 (HY000): Could not initialize master info structure; more error messages can be found in the MariaDB error log

于是看错误日志：/var/log/mariadb/mariadb.log

错误日志的位置在/etc/my.cnf中配置：log-error=/


[root@localhost ~]# cat /var/log/mariadb/mariadb.log
160915 12:52:02 [ERROR] Failed to open the relay log './mariadb-relay-bin.000001' (relay_log_pos 4)
160915 12:52:02 [ERROR] Could not find target log during relay log initialization

通过查找答案：删除/var/lib/mysql/路径下the ‘master.info' ‘mysqld-relay-bin.*' ‘relay-log.info' ‘relay-log-index.*'

运行命令：rm -rf master.info,rm -rf *relay*

重启服务：[root@localhost mysql]# systemctl restart mariadb.service

进入mariadb:


[root@localhost mysql]# mysql -u root -padmin
MariaDB [(none)]> flush logs;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> reset slave;
Query OK, 0 rows affected (0.00 sec)

重新设置主从复制关系：


MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='10.69.5.200',MASTER_USER='root', MASTER_PASSWORD='admin', MASTER_LOG_FILE='master-bin.000001', MASTER_LOG_POS= 694;
Query OK, 0 rows affected (0.02 sec)

这次成功了。


MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.01 sec)

查看从库状态：

MariaDB [(none)]> show slave status\G

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

Slave_IO_State: Connecting to master

Master_Host: 10.69.5.200

Master_User: root

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: master-bin.000001

Read_Master_Log_Pos: 694

Relay_Log_File: relay-bin.000001

Relay_Log_Pos: 4

Relay_Master_Log_File: master-bin.000001

Slave_IO_Running: Connecting

Slave_SQL_Running: Yes

···

Replicate_Ignore_Server_Ids:

Master_Server_Id: 0

1 row in set (0.00 sec)

发现问题2.Slave_IO_Running: Connecting

问题2.Slave_IO_Running: Connecting

查看错误日志

[root@localhost ~]# cat /var/log/mariadb/mariadb.log

···

160915 13:17:56 [Note] Slave SQL thread initialized, starting replication in log 'master-bin.000001' at position 694, relay log '/var/lib/mysql/relay-bin.000001' position: 4

160915 13:17:56 [ERROR] Slave I/O: error connecting to master 'root@10.69.5.200:3306' - retry-time: 60 retries: 86400 message: Can't connect to MySQL server on '10.69.5.200' (113), Error_code: 2003

这时运行telnet命令


[root@localhost ~]# telnet 10.69.5.200 3306

-bash: telnet: 未找到命令

安装telnet


[root@localhost ~]# yum -y install telnet-server.x86_64

安装成功后重启telnet服务


[root@localhost ~]# systemctl start telnet.socket
[root@localhost ~]# systemctl enable telnet.socket
[root@localhost ~]# telnet 10.69.5.200 3306

-bash: telnet: 未找到命令

还是不行

这回我reboot重启虚拟机，运行命令

注意：这回不是"yum -y install telnet-server.x86_64"了，这回没有telnet-server了


[root@localhost ~]# yum install telnet.x86_64

运行成功了

接着


[root@localhost ~]# systemctl enable telnet.socket
[root@localhost ~]# systemctl start telnet.socket
[root@localhost ~]# firewall-cmd --add-service=telnet --permanent 
success
[root@localhost ~]# telnet
telnet>

telnet终于安装成功了

从最新版本的centos7系统开始，默认的是 Mariadb而不是mysql！

使用系统自带的repos安装很简单：

yum install mariadb mariadb-server