MySQL master-slave replication
Experiment preparation:
2 MySQL servers:
master: 192.168.78.132
slave: 192.168.78.148
Master-slave replication principle
- Enable binary logging on the master
- When the data on the master changes, a binary log will be generated.
- The dump thread on the master will notify the io thread on the slave to get the binary log, and then write it to the slave's relay log. Then the SQL thread will read the newly generated relay log and replay the operations in the binary log, thereby achieving slave and The data on the master is exactly the same, maintaining consistency.
1. Enable binary logs
Enable binary logging on the master server,server_id=1
[root@mysql-master ~]# vim /etc/my.cnf
[mysqld]
...
#log bin
log_bin
server_id = 1
Binary logging can also be enabled on the slave server.server_id=2
[root@mysql-slave ~]# vim /etc/my.cnf
[mysqld]
...
#log bin
log_bin
server_id = 2
2. Synchronize database data
Export the contents of the master server database and then import it to the slave server
1.Export data on Master
[root@mysql-master ~]# mysqldump -uroot -p"Sanchuang123#" --all-databases >/backup/all_db.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
2. Import data into slave
Upload the data file to the slave server and import the data to achieve consistent initial data on the master and slave servers:
Operation on the master server:
#需要先建立免密通道
[root@mysql-master ~]# scp /backup/all_db.sql 192.168.78.148:/root
all_db.sql 100% 885KB 79.4MB/s 00:00
Operation on the slave server:
[root@mysql-slave ~]# mysql -uroot -p'Sanchuang123#' <all_db.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
3. Create a new authorized user
Refresh MySQL on the master server to generate a new log to facilitate subsequent operations:
root@(none) 19:33 mysql>flush logs;
Query OK, 0 rows affected (0.01 sec)
root@(none) 19:36 mysql>show master status; #查看当前正在使用的二进制日志文件
+-------------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------------+----------+--------------+------------------+-------------------+
| mysql-master-bin.000003 | 154 | | | |
+-------------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
Create a new user in MySQL on the master server:
root@(none) 19:36 mysql>grant replication slave on *.* to 'sc'@'192.168.78.%' identified by 'Sanchuang123#';
Query OK, 0 rows affected, 1 warning (0.00 sec)
root@(none) 19:41 mysql>flush privileges; #刷新 MySQL 权限
Query OK, 0 rows affected (0.00 sec)
root@(none) 19:42 mysql>show show grants for 'sc'@'192.168.78.%'; #用于显示指定用户在 MySQL 中的授权信息
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'show grants for 'sc'@'192.168.78.%'' at line 1
root@(none) 19:42 mysql>show grants for 'sc'@'192.168.78.%';
+-------------------------------------------------------+
| Grants for sc@192.168.78.% |
+-------------------------------------------------------+
| GRANT REPLICATION SLAVE ON *.* TO 'sc'@'192.168.78.%' |
+-------------------------------------------------------+
1 row in set (0.01 sec)
4. Configure on the slave server
root@(none) 19:58 mysql>CHANGE MASTER TO MASTER_HOST='192.168.78.132' ,
-> MASTER_USER='sc', #创建的授权用户
-> MASTER_PASSWORD='Sanchuang123#', #密码
-> MASTER_PORT=3306, #master的MySQL端口号
-> MASTER_LOG_FILE='mysql-master-bin.000003', #master正在使用的二进制文件
-> MASTER_LOG_POS=154; #二进制文件现在的pos
Query OK, 0 rows affected, 2 warnings (0.00 sec)
Check the status of the slave server:
root@(none) 19:58 mysql>show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.78.132
Master_User: sc
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-master-bin.000003
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-slave-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-master-bin.000003
Slave_IO_Running: No #从服务器的IO线程没有起来
Slave_SQL_Running: No #从服务器的SQL线程没有起来
Start the SQL thread:
root@(none) 20:01 mysql>stop slave; #停止从服务器上的主从复制
Query OK, 0 rows affected (0.00 sec)
root@(none) 20:03 mysql>start slave; #开启从服务器上的主从复制
Query OK, 0 rows affected (0.00 sec)
root@(none) 20:03 mysql>show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.78.132
Master_User: sc
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-master-bin.000003
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-slave-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-master-bin.000003
Slave_IO_Running: No
Slave_SQL_Running: Yes #发现sql线程开启成功，io没有成功
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: 154
Relay_Log_Space: 154
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: 1593
Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work. #发现io不成功是uuid问题
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1
Master_UUID:
Master_Info_File: /data/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp: 230717 20:03:35
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
ERROR:
No query specified
Solve the same problem with UUID:
root@(none) 20:07 mysql> show variables like "%uuid%";
+---------------+--------------------------------------+
| Variable_name | Value |
+---------------+--------------------------------------+
| server_uuid | 8cccc5f7-be7a-11ed-8855-000c29398d80 |
+---------------+--------------------------------------+
1 row in set (0.00 sec)
Just modify a few characters, just make it different from the ones in the main server:
[root@mysql-slave ~]# cd /data/mysql #MySQL数据目录
[root@mysql-slave mysql]# vim auto.cnf
[auto]
server-uuid=8cccc5f7-be7a-11ed-8855-000c29398d81
[root@mysql-slave mysql]# service mysqld restart
Shutting down MySQL.... SUCCESS!
Starting MySQL. SUCCESS!
Problem solved successfully:
root@(none) 20:09 mysql>show slave status\G;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 4
Current database: *** NONE ***
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.78.132
Master_User: sc
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-master-bin.000003
Read_Master_Log_Pos: 598
Relay_Log_File: mysql-slave-relay-bin.000003
Relay_Log_Pos: 771
Relay_Master_Log_File: mysql-master-bin.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
After success, view the file:
[root@mysql-slave mysql]# cat master.info
25
mysql-master-bin.000003
598
192.168.78.132
sc
Sanchuang123#
3306
60
0
0
30.000
0
8cccc5f7-be7a-11ed-8855-000c29398d80
86400
0
[root@mysql-slave mysql]# cat relay-log.info
7
./mysql-slave-relay-bin.000003
771
mysql-master-bin.000003
598
0
0
1
How does the Master know which slave servers there are?
root@(none) 19:51 mysql>SHOW SLAVE HOSTS;
+-----------+------+------+-----------+--------------------------------------+
| Server_id | Host | Port | Master_id | Slave_UUID |
+-----------+------+------+-----------+--------------------------------------+
| 2 | | 3306 | 1 | 8cccc5f7-be7a-11ed-8855-000c29398d81 |
+-----------+------+------+-----------+--------------------------------------+
1 row in set (0.00 sec)
5. Verify whether master-slave replication is successful
On the master server, create a database and tables:
root@(none) 20:16 mysql>create database db1;
Query OK, 1 row affected (0.00 sec)
root@(none) 20:19 mysql>use db1
Database changed
root@db1 20:19 mysql>create table t1(id int ,name varchar(20));
Query OK, 0 rows affected (0.01 sec)
root@db1 20:20 mysql> insert into t1 values(1,'lisi');
Query OK, 1 row affected (0.00 sec)
root@db1 20:20 mysql>select * from t1;
+------+------+
| id | name |
+------+------+
| 1 | lisi |
+------+------+
1 row in set (0.00 sec)
Check whether it exists on the slave server:
root@(none) 20:16 mysql>use db1
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
root@db1 20:22 mysql>select * from t1;
+------+------+
| id | name |
+------+------+
| 1 | lisi |
+------+------+
1 row in set (0.00 sec)