Configuring MySQL multi instance master-slave synchronization for Linux

notes : The master-slave synchronization configuration in this document is based on multiple instances Mysql

The content of this document is based on the following two blogs :

linux Lower installation MySQL5.7 And summarize the problems encountered

linux The configuration mysql Multiple instances

Document directory :

One . Introduction to master slave synchronization

Two . To configure MySQL Multi instance master-slave synchronization

• 2.1 Machine configuration
• 2.2 Modify the master server configuration
• 2.3 Modify slave server configuration
• 2.4 Enable master-slave synchronization and verify

3、 ... and . Linux To configure MySQL Problems encountered in multi instance master-slave synchronization

• 3.1 Fatal error: The slave I/O thread stops because master and slave have equal MySQL server ids
• 3.2 error connecting to master ‘[email protected]:3308’

One . Introduction to master slave synchronization

Master slave synchronization definition

Master-slave synchronization enables data to be replicated from one database server to another .
When copying data , A server acts as the primary server （master）, The rest of the servers act as slave servers （slave）.
Replication is done asynchronously .
Through the configuration file , You can specify to copy all databases , Some database , Even a table on a database .

Advantages of master-slave synchronization

1. Improve database performance , Write and update on the primary server , Provide read function from the server , You can dynamically adjust the number of slave servers , To adjust the performance of the entire database .
2. Improve data security , Because the data has been copied to the slave server , The replication process can be terminated from the server , therefore , It can be backed up on the slave server without destroying the corresponding data of the master server
3. Improve the performance of the primary server ( Read write separation reduces the pressure on the primary server )

Two . To configure MySQL Multi instance master-slave synchronization

2.1 Machine configuration

The server	operating system	ip Address	The port number corresponding to the instance	MySQL edition
The server 1( Lord )	CentOS7	192.168.226.136	3308	5.7.24
The server 2( from )	CentOS7	192.168.226.137	3308	5.7.24

Be careful : The master server needs to establish network communication with the slave server

2.2 Modify the master server configuration

Modify the configuration file

MySQL The default configuration : /etc/my.cnf

My multi instance configuration : /etc/mysql/3308/my.cnf

stay [mysqld] Add the following lines below .

server-id=3308
#log-bin Setting this parameter means enabling binlog function , And specify the path name 
log-bin=/var/lib/mysql/3308/mysql-bin
sync_binlog=0
# Set the expiration days of the log 
expire_logs_days=7
#binlog_cache_size This parameter represents binlog Memory size used 
binlog_cache_size=1M

restart MySQL database

After configuration modification , Need to restart MySQL Database for configuration to take effect .

Single instance restart mode :

service mysql restart

Multi instance restart mode :

#  Stop instance   The port number is not 3306 You need to specify the socket file 
/opt/modules/mysql/bin/mysqladmin -uroot -p123456 -S /var/lib/mysql/3308/mysql.sock shutdown  

#  Boot instance   When starting multiple instances, you need to specify my.cnf file 
nohup /bin/sh /opt/modules/mysql/bin/mysqld_safe --defaults-file=/etc/mysql/3308/my.cnf --user=mysql &

Create a synchronization data account , And empowering

Log in to the main server mysql

# MySQL Multiple instances require the use of -S Order to designate socket file 
mysql -uroot -p123456 -S /var/lib/mysql/3308/mysql.sock

Create an account for synchronizing data from the server

#  notes REPLICATION The operation authority on behalf of the user is copy  
# *.* Represents all tables in any database 
# % Match all host Address 
# 123456 refer to slave User's password 
GRANT REPLICATION SLAVE ON *.* TO 'slave'@'%' identified by '123456';
FLUSH PRIVILEGES;

Get binary log information of the primary server

show master status;

Be careful : File For the name of the log file used ,Position File location for use , These two parameters must be noted down , Configuration from the server will use

2.3 Modify slave server configuration

Server configuration modification

MySQL The default configuration : /etc/my.cnf

My multi instance configuration : /etc/mysql/3308/my.cnf

stay [mysqld] Add the following lines below

# server-id A unique identifier for a database service  
#  Be careful :  Uniqueness must be guaranteed here , Namely and master Of server-id atypism , Otherwise, an error will be reported when starting synchronization 
server-id=3309
#read_only Set the database to read-only , Prevent from modifying data from the library , The master and slave data are inconsistent , But there are Super The account with permission still has permission to write , So if you want an account to be read-only , You can remove the account number Super jurisdiction 
read_only=1

#binlog_cache_size This parameter represents binlog Memory size used 
binlog_cache_size=1M
expire_logs_days=10
max_binlog_size=100M

restart MySQL The database makes the configuration effective

#  Stop instance   The port number is not 3306 You need to specify the socket file 
/opt/modules/mysql/bin/mysqladmin -uroot -p123456 -S /var/lib/mysql/3308/mysql.sock shutdown  

#  Boot instance   Multiple instances need to be specified my.cnf file 
nohup /bin/sh /opt/modules/mysql/bin/mysqld_safe --defaults-file=/etc/mysql/3308/my.cnf --user=mysql &

2.4 Enable master-slave synchronization and verify

Connect the main library

#  Be careful : Default connection port 3306, If the port is not 3306, Need to use MASTER_PORT Specify port number 
# MASTER_LOG_FILE Log file name used by the primary server 
# MASTER_LOG_POS File location for use 
 CHANGE MASTER TO MASTER_HOST='192.168.226.136',MASTER_PORT=3308, MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000002', MASTER_LOG_POS=2478;

Start the synchronization

mysql> start slave;

View the slave library status

mysql> show slave status \G;

The two parameter statuses marked in the red box are YES, Prove that the synchronization configuration is normal , Otherwise, corresponding treatment shall be made according to the error prompt

After completion , The synchronization configuration needs to be refreshed

#  First stop synchronization 
mysql> stop slave;

#  Clean up the previous configuration , Prevent synchronization of already synchronized data 
mysql> reset slave all;

Finally, reconnect the main library , To synchronize

Synchronous verification

Here's the picture : master server test library –>user Insert a record below the table

From the server , First, the corresponding library table will be generated ( If not ), Then insert the corresponding record

Master slave synchronization is normal !

3、 ... and . Linux To configure MySQL Problems encountered in multi instance master-slave synchronization

3.1 Fatal error: The slave I/O thread stops because master and slave have equal MySQL server ids

Carry out orders show slave status \G; When viewing the synchronization status from the server , Report errors :

Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server ids;
these ids must be different for replication to work (or the --replicate-same-server-id option must be used on slave but this does not always make sense; 
please check the manual before using it).

Error reason : Master and slave servers server-id Agreement , Here are two servers , All of them are 3308 port , So when configuring server-id All configured 3308 Lead to conflict

Solution :
Modify one of the servers MySQL The configuration file , The default is /etc/my.cnf, modify server-id, Ensure that the master and slave are different

3.2 error connecting to master ‘[email protected]:3308’

An error is reported after the master-slave synchronization is enabled :

Last_IO_Error: error connecting to master '[email protected]:3308' - retry-time: 60  retries: 1

Error reason :

slave The connection of the account to the primary server is abnormal

Possible causes :

1. master server 3308 The instance corresponding to the port hangs
2. slave User permission setting problem , There is no corresponding authority

Solution :

If the instance hangs , You need to restart the corresponding instance of the primary server :

nohup /bin/sh /opt/modules/mysql/bin/mysqld_safe --defaults-file=/etc/mysql/3308/my.cnf --user=mysql &

If the user does not have the corresponding permission , Sign in MySQL Execute the following command :

GRANT REPLICATION SLAVE ON *.* TO 'slave'@'%' identified by '123456';
FLUSH PRIVILEGES;