Master-slave replication of database

1. Environment

master node	CentOS 7.6	192.168.111.132	mysql 5.7
slave node	CentOS 7.6	192.168.111.133	mysql 5.7

2. Synchronization time

## 下载ntp
yum -y install ntp
## 启动ntp
systemctl enable --now ntpd
## master节点
在/etc/ntp.conf文件尾部加入以下两段，注意网段。
server 127.127.111.0
fudge 127.127.111.0 stratum 8
## 重启ntp
systemctl restart ntpd


## slave节点
执行命令，IP地址为你master节点的IP地址
ntpdate 192.168.111.133

2. To achieve master-slave replication, there are three principles:

Add log-bin=mysql-bin to /etc/my.cnf to enable the binary log of the master node. This file will record our additions, deletions, checks, and modifications in the database.
The slave node copies the SQL statements in the binary file of the master node to its own relay log.
The salve node will copy the relay log to its own log and execute the sql command again.

1. Enable binary logs on the master node.

[root@master ~]# cat /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
log-bin=mysql-bin
server-id=1

2. Create an account for synchronization.

Among them, file and position we will use.

## 创建用户
create user 'repl'@'192.168.111.133' identified by '123456';
## 将创建的repl用户授权给192.168.111.133使用。
GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.111.133';
## 刷新权限
flush privileges;

查看我们的二进制文件
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 |     1079 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

3. Slave node configuration.

[root@slave ~]# cat /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
server-id=2

Fourth, initialize the database

Where master_host is the IP address of our master node. master_user is the user we authorized earlier. master_host is the user's password, master_log_file and master_log_pos are the two values that we generated the binary file earlier.

mysql> change master to master_host='192.168.111.132', master_user='repl', master_password='123456',master_log_file='mysql-bin.000001', master_log_pos=1079;
Query OK, 0 rows affected, 2 warnings (0.02 sec)

##  开启从节点.
mysql> start slave;

##  查看从数据库的状态
mysql> show slave status\G;

Among them, if salve_io_running and slave_sql_running are yes, it will succeed.

Master-slave replication of database

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