Amazon RDS (Relational Database Service)

Amazon Relational Database Service (RDS) is a managed service that makes it easy to set up, operate, and scale a relational database in the cloud. It handles time-consuming administration tasks so you can focus on your application.

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Why Use RDS?

Running a database on EC2 means you are responsible for:

• Installing and patching the database software
• Configuring backups and recovery
• Managing replication and failover
• Scaling storage and compute
• Monitoring performance

RDS automates all of this. You get a fully managed database with high availability, automated backups, and easy scaling.

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Supported Database Engines

Engine	Description
Amazon Aurora	AWS-built, MySQL/PostgreSQL-compatible, up to 5x faster
MySQL	Popular open-source relational database
PostgreSQL	Advanced open-source relational database
MariaDB	Community-developed fork of MySQL
Oracle	Enterprise relational database
SQL Server	Microsoft's relational database

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Key Features

Automated Backups

RDS automatically backs up your database and transaction logs:

• Backup retention: 1 to 35 days (default: 7 days)
• Point-in-time recovery: restore to any second within the retention period
• Backups are stored in S3 (managed by AWS)

Multi-AZ Deployments

For high availability, RDS can maintain a synchronous standby replica in a different Availability Zone:

Primary DB (AZ-a) ←— synchronous replication —→ Standby DB (AZ-b)

• Automatic failover if the primary fails (typically 60–120 seconds)
• The standby is not available for read traffic — it's purely for failover

Read Replicas

To scale read-heavy workloads, you can create read replicas:

• Up to 15 read replicas for Aurora, 5 for other engines
• Replicas can be in different regions (cross-region read replicas)
• Replication is asynchronous
• Read replicas can be promoted to standalone databases

Storage Auto Scaling

RDS can automatically increase storage when it detects you're running low, up to a maximum threshold you set.

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Instance Classes

RDS instance classes follow a similar pattern to EC2:

Class	Optimised For	Example
db.t	Burstable, development	db.t3.micro
db.m	General purpose	db.m6i.large
db.r	Memory optimised	db.r6i.large

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Security

Network Isolation