How to configure MySQL Multi-Master Replication on Oracle Linux

This tutorial explains how to setup and configure MySQL multi-master replication on Oracle Linux. As you all may already know, MySQL is a well known top notch database product that has proven to be enterprise ready. As data is crucial for every organization, most database administrators are looking for a suitable solution to setup high availability to ensure user are able to access their data 24/7. MySQL replication is a solution that can ensure a high availability policy. On top of that, MySQL replication is also able to help database administrators to distribute the load on multiple database servers by load balancing the READ and WRITE requests. Unfortunately, basic replication can only offer benefits on READ requests. Due to that, MySQL multi-master replication was introduced to offer replication for WRITE request as well.


1. Preliminary Note

For this tutorial, I am using Oracle Linux 6.8 in the 32bit version. Please note that even though the configuration is made under Oracle Linux, yet the steps and configuration are mainly the same to CentOS and Red Hat Linux. In this tutorial, we will use 2 servers. On each of them, we will set up a MySQL database and configure it for multi-master replication. At the end of this tutorial, we will see that any READ or WRITE request including DDL (Data Definition Language) and DML (Data Manipulation Language) requests will be run on both servers.


2. Installation Phase

For the installation phase, we do only require the MySQL server package for the configuration phase and MySQL client for accessing the database environment. Both packages do require some dependencies to be installed. First, let's confirm the version of our Operating System and note down the IP address for pre-configuration.


[root@DB1 ~]# lsb_release -a
LSB Version: :base-4.0-ia32:base-4.0-noarch:core-4.0-ia32:core-4.0-noarch:graphics-4.0-ia32:graphics-4.0-noarch:printing-4.0-ia32:printing-4.0-noarch
Distributor ID: OracleServer
Description: Oracle Linux Server release 6.8
Release: 6.8
Codename: n/a

[root@DB1 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 08:00:27:42:C0:4C
inet addr:192.168.43.11 Bcast:192.168.43.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fe42:c04c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:544 errors:0 dropped:0 overruns:0 frame:0
TX packets:79 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:51274 (50.0 KiB) TX bytes:9474 (9.2 KiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:240 (240.0 b) TX bytes:240 (240.0 b)

Now do the same on the other server.


[root@DB2 ~]# lsb_release -a
LSB Version: :base-4.0-ia32:base-4.0-noarch:core-4.0-ia32:core-4.0-noarch:graphics-4.0-ia32:graphics-4.0-noarch:printing-4.0-ia32:printing-4.0-noarch
Distributor ID: OracleServer
Description: Oracle Linux Server release 6.8
Release: 6.8
Codename: n/a

[root@DB2 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 09:00:30:42:C1:5D
inet addr:192.168.43.12 Bcast:192.168.43.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fe42:c04c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:544 errors:0 dropped:0 overruns:0 frame:0
TX packets:79 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:51274 (50.0 KiB) TX bytes:9474 (9.2 KiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:4 errors:0 dropped:0 overruns:0 frame:0
TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:240 (240.0 b) TX bytes:240 (240.0 b)

Next add the IP address to the server's hosts file. Do the same on both server like below.


[root@DB1 ~]# vi /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.43.11 DB1
192.168.43.12 DB2

Next, I will configure a new repository to install the MySQL server and MySQL client packages via yum utility. Please do this on BOTH servers.


[root@DB1 ~]# cd /etc/yum.repos.d/
[root@DB1 yum.repos.d]# ls
OEL6.repo

[root@DB1 yum.repos.d]# wget http://repo.mysql.com/mysql-community-release-el6-5.noarch.rpm
--2017-05-22 09:43:59-- http://repo.mysql.com/mysql-community-release-el6-5.noarch.rpm
Resolving repo.mysql.com... 23.8.231.210
Connecting to repo.mysql.com|23.8.231.210|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 5824 (5.7K) [application/x-redhat-package-manager]
Saving to: "mysql-community-release-el6-5.noarch.rpm"

100%[==================================================>] 5,824 --.-K/s in 0s

2017-05-22 09:44:00 (264 MB/s) - "mysql-community-release-el6-5.noarch.rpm" saved [5824/5824]

[root@DB1 yum.repos.d]# ls
OEL6.repo mysql-community-release-el6-5.noarch.rpm

[root@DB1 yum.repos.d]# rpm -Uvh mysql-community-release-el6-5.noarch.rpm
Preparing... ########################################### [100%]
1:mysql-community-release########################################### [100%]

[root@DB1 yum.repos.d]# ls
CentOS.repo mysql-community.repo
mysql-community-release-el6-5.noarch.rpm mysql-community-source.repo

The new repository for the latest MySQL version have been installed. Let's enable them.



[root@DB1 yum.repos.d]# vi mysql-community.repo
# Enable to use MySQL 5.6
[mysql56-community]
name=MySQL 5.6 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.6-community/el/6/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

Once done, let's ensure that the MySQL packages are available.



[root@DB1 yum.repos.d]# rpm -qa|grep -i mysql
mysql-community-release-el6-5.noarch

Great, now we've half way done. As no MySQL packages are installed in the current server, let's start the package installation. Below are the steps.

[root@DB1 yum.repos.d]#
[root@DB1 yum.repos.d]# yum install mysql-server mysql-client
Loaded plugins: fastestmirror, refresh-packagekit, security
Setting up Install Process
Repository 'OEL' is missing name in configuration, using id
Determining fastest mirrors
epel/metalink | 6.2 kB 00:00
* epel: epel.mirror.angkasa.id
* remi-php56: remi.mirror.wearetriple.com
* remi-safe: remi.mirror.wearetriple.com
OEL | 3.7 kB 00:00
epel | 4.3 kB 00:00
epel/primary_db | 5.9 MB 00:00
mysql-connectors-community | 2.5 kB 00:00
mysql-connectors-community/primary_db | 15 kB 00:00
mysql-tools-community | 2.5 kB 00:00
mysql-tools-community/primary_db | 35 kB 00:00
mysql56-community | 2.5 kB 00:00
mysql56-community/primary_db | 183 kB 00:00
remi-php56 | 2.9 kB 00:00
remi-php56/primary_db | 218 kB 00:01
remi-safe | 2.9 kB 00:00
remi-safe/primary_db | 725 kB 00:02
Package mysql-server is obsoleted by mysql-community-server, trying to install mysql-community-server-5.6.36-2.el6.i686 instead
No package mysql-client available.
Resolving Dependencies
--> Running transaction check
---> Package mysql-community-server.i686 0:5.6.36-2.el6 will be installed
--> Processing Dependency: mysql-community-common(i686) = 5.6.36-2.el6 for package: mysql-community-server-5.6.36-2.el6.i686
--> Processing Dependency: mysql-community-client(i686) >= 5.6.10 for package: mysql-community-server-5.6.36-2.el6.i686
--> Processing Dependency: perl(DBI) for package: mysql-community-server-5.6.36-2.el6.i686
--> Running transaction check
---> Package mysql-community-client.i686 0:5.6.36-2.el6 will be installed
--> Processing Dependency: mysql-community-libs(i686) >= 5.6.10 for package: mysql-community-client-5.6.36-2.el6.i686
---> Package mysql-community-common.i686 0:5.6.36-2.el6 will be installed
---> Package perl-DBI.i686 0:1.609-4.el6 will be installed
--> Running transaction check
---> Package mysql-community-libs.i686 0:5.6.36-2.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

============================================================================================
Package Arch Version Repository Size
============================================================================================
Installing:
mysql-community-server i686 5.6.36-2.el6 mysql56-community 55 M
Installing for dependencies:
mysql-community-client i686 5.6.36-2.el6 mysql56-community 18 M
mysql-community-common i686 5.6.36-2.el6 mysql56-community 308 k
mysql-community-libs i686 5.6.36-2.el6 mysql56-community 1.9 M
perl-DBI i686 1.609-4.el6 CentOS 705 k

Transaction Summary
============================================================================================
Install 5 Package(s)

Total download size: 76 M
Installed size: 338 M
Is this ok [y/N]: y
Downloading Packages:
(1/5): mysql-community-client-5.6.36-2.el6.i686.rpm | 18 MB 00:01
(2/5): mysql-community-common-5.6.36-2.el6.i686.rpm | 308 kB 00:00
(3/5): mysql-community-libs-5.6.36-2.el6.i686.rpm | 1.9 MB 00:00
(4/5): mysql-community-server-5.6.36-2.el6.i686.rpm | 55 MB 00:02
(5/5): perl-DBI-1.609-4.el6.i686.rpm | 705 kB 00:00
--------------------------------------------------------------------------------------------
Total 18 MB/s | 76 MB 00:04
warning: rpmts_HdrFromFdno: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Retrieving key from file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
Importing GPG key 0x5072E1F5:
Userid : MySQL Release Engineering <mysql-build@oss.oracle.com>
Package: mysql-community-release-el6-5.noarch (installed)
From : file:/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
Is this ok [y/N]: y
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
Installing : mysql-community-common-5.6.36-2.el6.i686 1/5
Installing : mysql-community-libs-5.6.36-2.el6.i686 2/5
Installing : mysql-community-client-5.6.36-2.el6.i686 3/5
Installing : perl-DBI-1.609-4.el6.i686 4/5
Installing : mysql-community-server-5.6.36-2.el6.i686 5/5
Verifying : perl-DBI-1.609-4.el6.i686 1/5
Verifying : mysql-community-server-5.6.36-2.el6.i686 2/5
Verifying : mysql-community-libs-5.6.36-2.el6.i686 3/5
Verifying : mysql-community-common-5.6.36-2.el6.i686 4/5
Verifying : mysql-community-client-5.6.36-2.el6.i686 5/5

Installed:
mysql-community-server.i686 0:5.6.36-2.el6

Dependency Installed:
mysql-community-client.i686 0:5.6.36-2.el6 mysql-community-common.i686 0:5.6.36-2.el6
mysql-community-libs.i686 0:5.6.36-2.el6 perl-DBI.i686 0:1.609-4.el6

Complete!

Excellent, now the installation is done. Start the MySQL daemon for the first time.


[root@DB1 yum.repos.d]# service mysqld restart
Stopping mysqld: [ OK ]
Initializing MySQL database: 2017-05-22 09:55:53 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2017-05-22 09:55:53 0 [Note] Ignoring --secure-file-priv value as server is running with --bootstrap.
2017-05-22 09:55:53 0 [Note] /usr/sbin/mysqld (mysqld 5.6.36) starting as process 18645 ...
2017-05-22 09:55:53 18645 [Note] InnoDB: Using atomics to ref count buffer pool pages
2017-05-22 09:55:53 18645 [Note] InnoDB: The InnoDB memory heap is disabled
2017-05-22 09:55:53 18645 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-05-22 09:55:53 18645 [Note] InnoDB: Memory barrier is not used
2017-05-22 09:55:53 18645 [Note] InnoDB: Compressed tables use zlib 1.2.3
2017-05-22 09:55:53 18645 [Note] InnoDB: Using Linux native AIO
2017-05-22 09:55:53 18645 [Note] InnoDB: Using CPU crc32 instructions
2017-05-22 09:55:53 18645 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2017-05-22 09:55:53 18645 [Note] InnoDB: Completed initialization of buffer pool
2017-05-22 09:55:53 18645 [Note] InnoDB: The first specified data file ./ibdata1 did not exist: a new database to be created!
2017-05-22 09:55:53 18645 [Note] InnoDB: Setting file ./ibdata1 size to 12 MB
2017-05-22 09:55:53 18645 [Note] InnoDB: Database physically writes the file full: wait...
2017-05-22 09:55:53 18645 [Note] InnoDB: Setting log file ./ib_logfile101 size to 48 MB
2017-05-22 09:55:53 18645 [Note] InnoDB: Setting log file ./ib_logfile1 size to 48 MB
2017-05-22 09:55:53 18645 [Note] InnoDB: Renaming log file ./ib_logfile101 to ./ib_logfile0
2017-05-22 09:55:53 18645 [Warning] InnoDB: New log files created, LSN=45781
2017-05-22 09:55:53 18645 [Note] InnoDB: Doublewrite buffer not found: creating new
2017-05-22 09:55:53 18645 [Note] InnoDB: Doublewrite buffer created
2017-05-22 09:55:53 18645 [Note] InnoDB: 128 rollback segment(s) are active.
2017-05-22 09:55:53 18645 [Warning] InnoDB: Creating foreign key constraint system tables.
2017-05-22 09:55:53 18645 [Note] InnoDB: Foreign key constraint system tables created
2017-05-22 09:55:53 18645 [Note] InnoDB: Creating tablespace and datafile system tables.
2017-05-22 09:55:53 18645 [Note] InnoDB: Tablespace and datafile system tables created.
2017-05-22 09:55:53 18645 [Note] InnoDB: Waiting for purge to start
2017-05-22 09:55:53 18645 [Note] InnoDB: 5.6.36 started; log sequence number 0
2017-05-22 09:55:54 18645 [Note] Binlog end
2017-05-22 09:55:54 18645 [Note] InnoDB: FTS optimize thread exiting.
2017-05-22 09:55:54 18645 [Note] InnoDB: Starting shutdown...
2017-05-22 09:55:55 18645 [Note] InnoDB: Shutdown completed; log sequence number 1625977


2017-05-22 09:55:55 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2017-05-22 09:55:55 0 [Note] Ignoring --secure-file-priv value as server is running with --bootstrap.
2017-05-22 09:55:55 0 [Note] /usr/sbin/mysqld (mysqld 5.6.36) starting as process 18667 ...
2017-05-22 09:55:55 18667 [Note] InnoDB: Using atomics to ref count buffer pool pages
2017-05-22 09:55:55 18667 [Note] InnoDB: The InnoDB memory heap is disabled
2017-05-22 09:55:55 18667 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-05-22 09:55:55 18667 [Note] InnoDB: Memory barrier is not used
2017-05-22 09:55:55 18667 [Note] InnoDB: Compressed tables use zlib 1.2.3
2017-05-22 09:55:55 18667 [Note] InnoDB: Using Linux native AIO
2017-05-22 09:55:55 18667 [Note] InnoDB: Using CPU crc32 instructions
2017-05-22 09:55:55 18667 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2017-05-22 09:55:55 18667 [Note] InnoDB: Completed initialization of buffer pool
2017-05-22 09:55:55 18667 [Note] InnoDB: Highest supported file format is Barracuda.
2017-05-22 09:55:55 18667 [Note] InnoDB: 128 rollback segment(s) are active.
2017-05-22 09:55:55 18667 [Note] InnoDB: Waiting for purge to start
2017-05-22 09:55:55 18667 [Note] InnoDB: 5.6.36 started; log sequence number 1625977
2017-05-22 09:55:55 18667 [Note] Binlog end
2017-05-22 09:55:55 18667 [Note] InnoDB: FTS optimize thread exiting.
2017-05-22 09:55:55 18667 [Note] InnoDB: Starting shutdown...
2017-05-22 09:55:57 18667 [Note] InnoDB: Shutdown completed; log sequence number 1625987




PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:

/usr/bin/mysqladmin -u root password 'new-password'
/usr/bin/mysqladmin -u root -h vdevknime1 password 'new-password'

Alternatively you can run:

/usr/bin/mysql_secure_installation

which will also give you the option of removing the test
databases and anonymous user created by default. This is
strongly recommended for production servers.

See the manual for more instructions.

Please report any problems at http://bugs.mysql.com/

The latest information about MySQL is available on the web at

http://www.mysql.com

Support MySQL by buying support/licenses at http://shop.mysql.com

Note: new default config file not created.
Please make sure your config file is current

WARNING: Default config file /etc/my.cnf exists on the system
This file will be read by default by the MySQL server
If you do not want to use this, either remove it, or use the
#NAME?

[ OK ]
Starting mysqld: [ OK ]

Great, now our MySQL server service is up. Let's confirm it by listing the port used by the MySQL service. By default, MySQL will use port 3306 when starting up the service. Below are the commands:


[root@DB1 yum.repos.d]# netstat -apn|grep -i mysql
tcp 0 0 :::3306 :::* LISTEN 2139/mysqld
unix 2 [ ACC ] STREAM LISTENING 16018 2139/mysqld /var/lib/mysql/mysql.sock 

Now, let's setup an initial password for the MySQL root user to ensure we didn't miss out the basic security for our MySQL server.


[root@DB1 yum.repos.d]# mysqladmin -u root password "Pass1234"
Warning: Using a password on the command line interface can be insecure.

[root@DB1 yum.repos.d]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.36 MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user();
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)

Done with the installation phase. Let's move on to the configuration of the multi-master replication setup.

3. Configuration Phase

Let's go inside the MySQL my.cnf configuration file and make the changes like below on server DB1.


[root@DB1 ~]# vi /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
port=3306
innodb_file_per_table=ON
pid-file=/var/lib/mysql/mysqld.pid

server-id = 11
log_bin = /var/log/mysql/mysql-bin.log
binlog_do_db = test_rep

Below is the explaination for the configuration:

  • server-id ==> The replication ID
  • log_bin ==> The log file to be use for replication activity
  • binlog_do_db ==> The database that related for replication process

Once done, let's go inside the MySQL server environment and create the related database and assign a user for the replication process.

[root@DB1 ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.01 sec)

mysql> create database test_rep;
Query OK, 1 row affected (0.01 sec)

mysql> create user 'replicator'@'DB2' identified by 'Rep1234';
Query OK, 0 rows affected (0.01 sec)

mysql> grant replication slave on *.* to 'replicator'@'DB2';
Query OK, 0 rows affected (0.00 sec) 

Done, now restart the MySQL server and see if the configuration has been activated or not. Below are the steps:

[root@DB1 yum.repos.d]# service mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]

[root@DB1 ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show master status;
+-------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 854 | test_rep | | |
+-------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec) 

Excellent, now let's setup server DB2 to be a slave server for the DB1 replication master and on top of that setting up the server DB2 also as a master for DB1 server. Below are the steps:

[root@DB2 ~]# vi /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
port=3306
innodb_file_per_table=ON
pid-file=/var/lib/mysql/mysqld.pid

server-id = 12
log_bin = /var/log/mysql/mysql-bin.log
binlog_do_db = test_rep 

Same like configuration in DB1, let's go inside the MySQL server environment and create the related database and assign a user for the replication process.

[root@DB2 ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.01 sec)

mysql> create database test_rep;
Query OK, 1 row affected (0.01 sec)

mysql> create user 'replicator'@'DB1' identified by 'Rep1234';
Query OK, 0 rows affected (0.01 sec)

mysql> grant replication slave on *.* to 'replicator'@'DB1';
Query OK, 0 rows affected (0.00 sec)

mysql> show slave status;
Empty set (0.01 sec)

Done, now let's restart the DB2 MySQL server and see if the if the configuration has been activated or not. If yes, then we continue to proceed with the creation of the slave for DB1 server.


[root@DB2 ~]# service mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]

[root@DB2 ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show master status;
+-------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 553 | test_rep | | |
+-------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql> stop slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> CHANGE MASTER TO MASTER_HOST = 'DB1', MASTER_PORT = 3306, MASTER_USER = 'replicator', MASTER_PASSWORD = 'Rep1234', MASTER_LOG_FILE = 'mysql-bin.000001', MASTER_LOG_POS = 854;
Query OK, 0 rows affected, 2 warnings (0.07 sec)

mysql> start slave;
Query OK, 0 rows affected (0.04 sec)

mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: DB1
Master_User: replicator
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 854
Relay_Log_File: mysqld-relay-bin.000002
Relay_Log_Pos: 284
Relay_Master_Log_File: mysql-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: 854
Relay_Log_Space: 459
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: 11
Master_UUID: 6e143d91-3635-11e7-b9ad-08002742c04c
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
1 row in set (0.00 sec)

ERROR:
No query specified


mysql> show slave status;
+----------------------------------+---------------+-------------+-------------+---------------+-------------------+---------------------+--------------------------+---------------+-----------------------+------------------+-------------------+-----------
| Slave_IO_State | Master_Host | Master_User | Master_Port | Connect_Retry | Master_Log_File | Read_Master_Log_Pos | Relay_Log_File | Relay_Log_Pos | Relay_Master_Log_File | Slave_IO_Running | Slave_SQL_Running | Replicate_Do_DB | Replicate_Ignore_DB | Replicate_Do_Table | Replicate_Ignore_Table | Replicate_Wild_Do_Table | Replicate_Wild_Ignore_Table | Last_Errno | Last_Error | Skip_Counter | Exec_Master_Log_Pos | Relay_Log_Space | Until_Condition | Until_Log_File | Until_Log_Pos | Master_SSL_Allowed | Master_SSL_CA_File | Master_SSL_CA_Path | Master_SSL_Cert | Master_SSL_Cipher | Master_SSL_Key | Seconds_Behind_Master | Master_SSL_Verify_Server_Cert | Last_IO_Errno | Last_IO_Error | Last_SQL_Errno | Last_SQL_Error | Replicate_Ignore_Server_Ids | Master_Server_Id | Master_UUID | Master_Info_File | SQL_Delay | SQL_Remaining_Delay | Slave_SQL_Running_State | Master_Retry_Count | Master_Bind | Last_IO_Error_Timestamp | Last_SQL_Error_Timestamp | Master_SSL_Crl | Master_SSL_Crlpath | Retrieved_Gtid_Set | Executed_Gtid_Set | Auto_Position |
+----------------------------------+---------------+-------------+-------------+---------------+-------------------+---------------------+--------------------------+---------------+-----------------------+------------------+-------------------+-----------
| Waiting for master to send event | DB1 | replicator | 3306 | 60 | mysql-bin.000001 | 854 | mysqld-relay-bin.000002 | 284 | mysql-bin.000001 | Yes | Yes | | | | | | | 0 | | 0 | 854 | 459 | None | | 0 | No | | | | | | 0 | No | 0 | | 0 | | | 11 | 6e143d91-3635-11e7-b9ad-08002742c04c | /var/lib/mysql/master.info | 0 | NULL | Slave has read all relay log; waiting for the slave I/O thread to update it | 86400 | | | | | | | | 0 |
+----------------------------------+---------------+-------------+-------------+---------------+-------------------+---------------------+--------------------------+---------------+-----------------------+------------------+-------------------+-----------
1 row in set (0.00 sec) 

Great! As everything has been setup for DB2 server, let go back to DB1 server and make the slave configuration for the DB2 server.

[root@DB1 ~]# mysql -u root -p
Enter password:
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show master status;
+-------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 854 | test_rep | | |
+-------------------+----------+--------------+------------------+-------------------+
1 row in set (0.01 sec)

mysql> stop slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> CHANGE MASTER TO MASTER_HOST = 'DB2', MASTER_PORT = 3306, MASTER_USER = 'replicator', MASTER_PASSWORD = 'Rep1234', MASTER_LOG_FILE = 'mysql-bin.000001', MASTER_LOG_POS = 553;
Query OK, 0 rows affected, 2 warnings (0.25 sec)

mysql> start slave;
Query OK, 0 rows affected (0.03 sec)

mysql> show slave status;
+----------------------------------+---------------+-------------+-------------+---------------+-------------------+---------------------+--------------------------+---------------+-----------------------+------------------+-------------------+-----------
| Slave_IO_State | Master_Host | Master_User | Master_Port | Connect_Retry | Master_Log_File | Read_Master_Log_Pos | Relay_Log_File | Relay_Log_Pos | Relay_Master_Log_File | Slave_IO_Running | Slave_SQL_Running | Replicate_Do_DB | Replicate_Ignore_DB | Replicate_Do_Table | Replicate_Ignore_Table | Replicate_Wild_Do_Table | Replicate_Wild_Ignore_Table | Last_Errno | Last_Error | Skip_Counter | Exec_Master_Log_Pos | Relay_Log_Space | Until_Condition | Until_Log_File | Until_Log_Pos | Master_SSL_Allowed | Master_SSL_CA_File | Master_SSL_CA_Path | Master_SSL_Cert | Master_SSL_Cipher | Master_SSL_Key | Seconds_Behind_Master | Master_SSL_Verify_Server_Cert | Last_IO_Errno | Last_IO_Error | Last_SQL_Errno | Last_SQL_Error | Replicate_Ignore_Server_Ids | Master_Server_Id | Master_UUID | Master_Info_File | SQL_Delay | SQL_Remaining_Delay | Slave_SQL_Running_State | Master_Retry_Count | Master_Bind | Last_IO_Error_Timestamp | Last_SQL_Error_Timestamp | Master_SSL_Crl | Master_SSL_Crlpath | Retrieved_Gtid_Set | Executed_Gtid_Set | Auto_Position |
+----------------------------------+---------------+-------------+-------------+---------------+-------------------+---------------------+--------------------------+---------------+-----------------------+------------------+-------------------+-----------
| Waiting for master to send event | DB2 | replicator | 3306 | 60 | mysql-bin.000001 | 553 | mysqld-relay-bin.000002 | 284 | mysql-bin.000001 | Yes | Yes | | | | | | | 0 | | 0 | 553 | 459 | None | | 0 | No | | | | | | 0 | No | 0 | | 0 | | | 12 | 14f5ab41-3c7b-11e7-a293-08002742c04c | /var/lib/mysql/master.info | 0 | NULL | Slave has read all relay log; waiting for the slave I/O thread to update it | 86400 | | | | | | | | 0 |
+----------------------------------+---------------+-------------+-------------+---------------+-------------------+---------------------+--------------------------+---------------+-----------------------+------------------+-------------------+-----------
1 row in set (0.01 sec)

mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: DB2
Master_User: replicator
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 553
Relay_Log_File: mysqld-relay-bin.000002
Relay_Log_Pos: 284
Relay_Master_Log_File: mysql-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: 553
Relay_Log_Space: 459
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: 12
Master_UUID: 14f5ab41-3c7b-11e7-a293-08002742c04c
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
1 row in set (0.00 sec)

ERROR:
No query specified 

Nicely done, now as everything is ready in place, let's proceed with the testing phase to conclude all configuration was made correctly.

4. Testing Phase

Before we start the test, let's make the assumptions for the final result expectations. For this test, we will create a table on DB1 MySQL server then on DB2 we will check if the table automatically exists or not. If yes then we will add a new data row into it and check again in DB1 server if new data is available on both servers.


[root@DB1 ~]# mysql -u root -p test_rep
Enter password:
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select database();
+------------+
| database() |
+------------+
| test_rep |
+------------+
1 row in set (0.00 sec)

mysql> create table tbl1( id int(11) primary key auto_increment, fullname varchar(30));
Query OK, 0 rows affected (0.22 sec)

mysql> show tables in test_rep;
+--------------------+
| Tables_in_test_rep |
+--------------------+
| tbl1 |
+--------------------+
1 row in set (0.01 sec) 

Done, as the table creation is a DDL (Data Definition Language) statement, there's no need to enter a commit command. Now let's go inside DB2 MySQL server and see if the newly table created exists.

[root@DB2 ~]# mysql -u root -p test_rep
Enter password:
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show tables in test_rep;
+--------------------+
| Tables_in_test_rep |
+--------------------+
| tbl1 |
+--------------------+
1 row in set (0.00 sec)

mysql> insert into tbl1 ( fullname ) values ('Shahril'), ('mark'), ('Allen'), ('Suzy'), ('Adam') ;
Query OK, 5 rows affected (0.05 sec)
Records: 5 Duplicates: 0 Warnings: 0

mysql> select * from tbl1;
+----+----------+
| id | fullname |
+----+----------+
| 1 | Shahril |
| 2 | mark |
| 3 | Allen |
| 4 | Suzy |
| 5 | Adam |
+----+----------+
5 rows in set (0.00 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec) 

Excellent, notice that the newly table created table in DB1 server now automatically exists in DB2 MySQL server. Then we also managed to insert 5 rows of data into the table. For the final check, let's see if the updated rows in table TBL1 can be seen in DB1 server as well.


[root@DB1 ~]# mysql -u root -p test_rep
Enter password:
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.6.36-log MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select * from tbl1;
+----+----------+
| id | fullname |
+----+----------+
| 1 | Shahril |
| 2 | mark |
| 3 | Allen |
| 4 | Suzy |
| 5 | Adam |
+----+----------+
5 rows in set (0.01 sec)

mysql> delete from tbl1 where fullname like 'A%';
Query OK, 2 rows affected (0.07 sec)

mysql> select * from tbl1;
+----+----------+
| id | fullname |
+----+----------+
| 1 | Shahril |
| 2 | mark |
| 4 | Suzy |
+----+----------+
3 rows in set (0.00 sec) 

Thumbs up! We've successfully created a MySQL multi-master replication between 2 servers.

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1 Comment(s)

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Comments

From: Joerg Bruehe at: 2017-06-29 11:17:58

Hi!

I'm missing a configuration setting which I consider essential:

"log_slave_updates = 1" should be set on both sides.

If you don't do that, you will run into (at least) two problems:

1) If you ever need the binlogs for anything, especially point-in-time recovery, you must take them from both hosts.

2) If you (later) add a slave to the setup, it will receive only some of the changes.

Regards,

Jörg