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Create A Read Replica In AWS RDS

In this article, we will create a read replica of the database in AWS.

Purpose

The read replica creates a read-only copy of the database and asynchronously synchronizes it from the actual database.

Why Do We Need To Create The “Read Replica” Of The Database?

The read replica serves 2 purposes: -

It helps in disaster recovery in case of database failover
It is easy to migrate from one data center to another

What Are The Database Instances For Which Read Replicas Can Be Created?

You can create the read replica for MariaDB, MySQL, Oracle, or PostgreSQL DB instances.

How To Create A "Read Replica"?

In this article, we will create a read replica of the MySQL database. The first step is to create the AWS RDS database instance. Follow this link for database creation.

Once the instance is created, select the database, and go to Actions → Create read replica.

Picture showing the Create read replica option for creating the read replica

Click to Enlarge

A screen will appear to enter the replica details. Enter the required details and click on the Create read replica button.

Picture showing the create read replica screen

Click to Enlarge

The read replica is created for the MySQL database.

Picture showing the read replica created for MySQL database

Click to Enlarge

How Does Read Replica Work?

In case of failover and the primary database is unavailable, the read replica database is promoted as the primary database.

The read replica will be assigned a new DNS endpoint.

Difference Between Multi-AZ and Read Replicas

Multi-AZ Deployments	Read Replicas
Synchronous Replication – highly durable	Asynchronous replication – highly scalable
Only the database engine on the primary instance is active	All read replicas are accessible and can be used for read scaling
Automated backups are taken from standby	No backups configured by default
Always span two availability zones within a single region	Can be within an Availability Zone, Cross-AZ, or Cross-Region
Database engine version upgrades happen on the primary	Database engine version upgrade is independent of the source instance
Automatic failover to standby when a problem is detected	Can be manually promoted to a standalone database instance

Posted By -	Karan Gupta

Posted On -	Wednesday, December 15, 2021

Updated On -	Tuesday, July 4, 2023

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