Amazon Relational Database Service (RDS)
Updated: Nov 10, 2020
In this article we shall look into what Amazon RDS is, its flavours, and benefits in a summarized presentation slider format. I hope this will be very much useful for beginners and for those who prepare for AWS exams.

What is Amazon RDS?
Amazon RDS is a managed relational database service provided on the cloud by Amazon Web Services.
RDS is web service that aims to facilitate the process of setting up, deploying, and scaling a relational database in the cloud.
It is easy to set-up, operate and scale, as necessary.
It provides cost-efficient and resizable capacity while automating time-consuming administration tasks such as hardware provisioning, database setup, patching and backups.
Why should we use Amazon RDS?
It is simple to use and easy to manage.
It is highly scale-able (Up and down).
It has high availability as it supports Multi-AZ.
It is durable as it does take automated backups, host replacement in case of failures and snapshots.
It can be easily monitored using Cloud watch metrics.
It is secure, as your data can be encrypted at rest or in transit.
It is cost efficient as you just pay monthly for each instance.
How RDS works in VPC - Read Replica Scenario
The diagram on the right shows how RDS works in Replication.

In this scenario, most of the read write requests are sent to Master DB while read only requests are sent to Replica, in order to minimize load on Master DB.
RDS is launched in a DB Subnet group containing 2 private subnets (each in a separate AZ).
RDS can support Multi-AZ deployment.
One instance in RDS is treated as Master whereas the other instance (in second availability zone) is treated as Replica.
Once launched both will be visible in RDS console.
Both instances will have individual endpoint URLs.
How RDS works in VPC - Multi-AZ Standby scenario
The diagram on the right shows how RDS works in Multi AZ scenario without replication.

In this scenario, the replica instance is not launched. So, when Master DB instance becomes unhealthy due to some reason or rebooted, Standby DB instance automatically spins up as Master DB immediately.
RDS is launched in a DB Subnet group containing 2 private subnets (each in a separate AZ).
RDS needs atleast 2 Availability Zones in a Multi-AZ scenario.
Frequent snapshots are automatically taken from Master DB.
Both instances will have same endpoints.
What are the engines supported by RDS?
Amazon RDS supports the following database engines.
Amazon Aurora: Up to five times faster than standard MySQL databases and three times faster than standard PostgreSQL databases.
Postgre SQL: The PostgreSQL-compatible edition of Aurora delivers up to 3X the throughput of standard PostgreSQL running on the same hardware, enabling existing PostgreSQL applications and tools to run without requiring modification
MySQL: Amazon RDS for MySQL frees you up to focus on application development by managing time-consuming database administration tasks including backups, software patching, monitoring, scaling and replication.
MariaDB: MariaDB is a popular open source relational database created by the original developers of MySQL. Amazon RDS makes it easy to set up, operate, and scale MariaDB server deployments in the cloud.
Oracle: Amazon RDS for Oracle is a fully managed commercial database that makes it easy to set up, operate, and scale Oracle deployments in the cloud.
Microsoft SQL Server: SQL Server is a relational database management system developed by Microsoft. Amazon RDS for SQL Server makes it easy to set up, operate, and scale SQL Server deployments in the cloud.
I believe the above information in 6-sliders presentation format will be helpful for beginners and AWS exam preparation. The above is just key information on Amazon RDS. For more detailed information, I would recommend you to study the documentation provided by Amazon.
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