Implementing Replication

1. Introduction

Replication is the process of copying and maintaining database objects, such as databases or tables, in multiple locations. It is a critical component in achieving high availability and scalability in database systems.

2. Types of Replication

There are several types of replication methods:

• Master-Slave Replication: A single master node handles the write operations, while one or more slave nodes replicate the data from the master.
• Master-Master Replication: Multiple nodes can handle both read and write operations, and changes are synchronized between them.
• Peer-to-Peer Replication: Each node is equal and can accept read and write requests, ensuring data consistency across nodes.

3. Setting Up Replication

3.1 Master-Slave Replication Setup Example (MySQL)

-- On the Master Server
-- Edit the MySQL configuration file (my.cnf)
[mysqld]
server-id = 1
log_bin = mysql-bin

-- Restart MySQL server
sudo service mysql restart

-- Create a replication user
CREATE USER 'replica_user'@'%' IDENTIFIED BY 'password';
GRANT REPLICATION SLAVE ON *.* TO 'replica_user'@'%';

-- On the Slave Server
-- Edit the MySQL configuration file (my.cnf)
[mysqld]
server-id = 2

-- Restart MySQL server
sudo service mysql restart

-- Configure the slave to connect to the master
CHANGE MASTER TO
MASTER_HOST='master_ip',
MASTER_USER='replica_user',
MASTER_PASSWORD='password',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=4;

-- Start the slave
START SLAVE;

3.2 Master-Master Replication Setup Example (MySQL)

-- On both servers
-- Edit the MySQL configuration file (my.cnf)
[mysqld]
server-id = 1
log_bin = mysql-bin
auto_increment_increment = 2
auto_increment_offset = 1

-- Restart MySQL server
sudo service mysql restart

-- Create a replication user on both servers
CREATE USER 'replica_user'@'%' IDENTIFIED BY 'password';
GRANT REPLICATION SLAVE ON *.* TO 'replica_user'@'%';

-- On Server 1
CHANGE MASTER TO
MASTER_HOST='server_2_ip',
MASTER_USER='replica_user',
MASTER_PASSWORD='password',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=4;

START SLAVE;

-- On Server 2
CHANGE MASTER TO
MASTER_HOST='server_1_ip',
MASTER_USER='replica_user',
MASTER_PASSWORD='password',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=4;

START SLAVE;

4. Best Practices

1. Ensure network reliability between replication nodes.
2. Regularly monitor replication status and lag.
3. Implement proper security measures for replication connections.
4. Test failover and recovery procedures periodically.
5. Consider data consistency and conflict resolution strategies.

5. FAQ