Redis Replication Tutorial

Introduction to Replication

Replication is a critical feature in Redis that allows data to be copied from one Redis server (the master) to one or more Redis servers (the replicas). This helps in improving availability, balancing the load, and ensuring data redundancy.

Setting Up Replication

To set up replication, follow these steps:

Step 1: Configure the master server. Ensure your Redis master server is running.

Step 2: Configure the replica servers. Add the following line to your replica's redis.conf file:

For example, if your master is running on 192.168.1.100 and port 6379, you would use:

Verifying Replication

To verify that replication is working correctly, start the Redis replica server and then run the info replication command on the replica:

You should see output similar to this:

# Replication
role:slave
master_host:192.168.1.100
master_port:6379
master_link_status:up
                

Handling Master Failures

If the master fails, the replicas can be promoted to masters to ensure continued availability. This process can be manually executed by using the slaveof no one command on the replica that you want to promote.

After running this command, the replica will become a master.

Reconfiguring after Failover

Once the master is back up, you may need to reconfigure the replication setup. To do this, you can use the slaveof command on the previous master to make it a replica of the new master.

Advanced Configuration Options

Redis offers several advanced options for replication, such as configuring the replica to serve reads, setting a replica read-only, and adjusting the replica priority for automatic failover. These options can be set in the redis.conf file.

For example, to set a replica to read-only mode, add the following line: