Amazon RDS - Relational Database Service and Amazon Aurora - AWS Certification Cheat Sheet

Let’s get a quick overview of Amazon RDS from an AWS certification perspective. We will look at important certification questions regarding Amazon RDS.

You will learn

  • What is Amazon RDS?
  • What are the different database options provided by Amazon RDS?
  • What are the important features of Amazon RDS?
  • What are the responsibilities of AWS/Customer when using Amazon RDS?
  • When do we use Amazon RDS?
  • How is Amazon Aurora different from other Amazon RDS databases ?
  • What is Amazon Aurora?
  • How do you implement encryption for Amazon RDS in integration with KMS?

Table of Contents

Amazon RDS (Relational Database Service)

Do you want to manage the setup, backup, scaling, replication and patching of your relational databases? Or do you want to use a managed service?

Amazon RDS is a managed relational database service for OLTP use cases


  • Amazon Aurora
  • PostgreSQL
  • MySQL (InnoDB storage engine full supported)
  • MariaDB (Enhanced MySQL)
  • Oracle Database
  • Microsoft SQL Server

Amazon RDS - Features

Some of the important Amazon RDS features include:

  • Multi-AZ deployment (standby in another AZ)
  • Read replicas:
    • Same AZ
    • Multi AZ (Availability+)
    • Cross Region(Availability++)
  • Storage auto scaling (up to a configured limit)
  • Automated backups (restore to point in time)
  • Manual snapshots

Amazon RDS - You vs AWS

Who is responsible for what when you use Amazon RDS?

AWS is responsible for

  • Availability (according to your configuration)
  • Durability
  • Scaling (according to your configuration)
  • Maintenance (patches)
  • Backups

You are responsible for

  • Managing database users
  • App optimization (tables, indexes etc)


  • SSH into database EC2 instances or setup custom software (NOT ALLOWED)
  • Install OS or DB patches. RDS takes care of them (NOT ALLOWED)

Amazon Aurora

Amazon Aurora is one of the database options supported by Amazon RDS.

Here are some of the important things to remember about Amazon Aurora:

  • MySQL and PostgreSQL-compatible
  • 2 copies of data each in a minimum of 3 AZ
  • Up to 15 read replicas (Only 5 for MySQL)
  • Uses cluster volume (multi AZ storage)

Amazon Aurora Provides “Global Database” option:

  • Up to five read-only, secondary AWS Regions
    • Low latency for global reads
    • Safe from region-wide outages
  • Minimal lag time, typically less than 1 second

Here are some of the deployment options with Amazon Aurora:

  • Single master (One writer and multiple readers)
  • Multi master deployment (multiple writers)
  • Serverless

RDS - Scaling

How do you scale RDS?

Let’s look at some of the options:

Vertical Scaling

Change DB instance type and scale storage

  • Storage and compute changes are typically applied during maintenance window
  • You can also choose to “apply-immediately”
  • RDS would take care of data migration
    • Takes a few minutes to complete
  • You can manually scale Aurora, MySQL, MariaDB, Oracle, and PostgreSQL engines to 64 TB
  • SQL Server can be scaled up to 16 TB

RDS also supports auto scaling storage.

Horizontal Scaling

You can configure Read Replicas.

Aurora provides additional options (Multi-master, Writer with multiple readers etc).

RDS - Operations

RDS console shows metrics upto a certain time period.

You can see historical data in CloudWatch.

Here are some of the recommedations:

  • Configure CloudWatch alarms to alert when you near max capacity
  • Enable Enhanced Monitoring to monitor slow queries

You can configure an Automatic backup during backup window (to Amazon S3)

  • Enables restore to point in time
  • Backups retained for 7 days by default (max - 35 days)
  • Elevated latency when snapshots are taken (except for Multi-AZ setup)
  • Backup window used to apply patches
    • If you do not configure a 30 minute backup window, RDS chooses one randomly
  • Achieve RPO of up to 5 minutes

RDS - Security and Encryption

Here are the important things to consider about Security of RDS:

  • Create in a VPC private subnet
  • Use security groups to control access
  • Enable encryption with keys from KMS

Here are some of the important security features supported by RDS:

  • Option to use IAM Authentication with Aurora, MySQL and PostgreSQL
    • Use IAM roles and no need for passwords
  • When encryption is enabled
    • Data in the database, automated backups, read replicas and snapshots are all encrypted
  • Data In-flight Encryption
    • Using SSL certificates

RDS - Costs - Key Elements

Key elements of RDS Costs include:

  • DB instance hours - How many hours is the DB instance running?
  • Storage (per GB per month) - How much storage have you provisioned for your DB instance?
  • Provisioned IOPS per month - If you are using Amazon RDS Provisioned IOPS (SSD) Storage
  • Backups and snapshot storage (across multi AZ) - More backups, More snapshots => More cost
  • Data transfer costs

Amazon RDS - When to use?

When do you use Amazon RDS?

Use Amazon RDS for transactional applications needing

  • Pre-defined schema
  • Strong transactional capabilities
  • Complex queries

Amazon RDS is NOT recommended when

  • You need highly scalable massive read/write operations - for example millions of writes/second
    • Go for DynamoDB
  • When you want to upload files using simple GET/PUT REST API
    • Go for Amazon S3
  • When you need heavy customizations for your database or need access to underlying EC2 instances
    • Go for a custom database installation

Amazon RDS - Certification and Interview Questions

Here are some of important scenarios and questions regarding Amazon RDS.

Scenario Solution
You want full control of OS or need elevated permissions Consider going for a custom installation (EC2 + EBS)
You want to migrate data from an on-premise database to cloud database of the same type Consider using AWS Database Migration Service
You want to migrate data from one database engine to another (Example : Microsoft SQL Server to Amazon Aurora) Consider using AWS Schema Conversion Tool
What are retained when you delete a RDS database instance? All automatic backups are deleted
All manual snapshots are retained (until explicit deletion)
(Optional) Take a final snapshot
How do you reduce global latency and improve disaster recovery? Use multi region read replicas
How do you select the subnets a RDS instance is launched into? Create DB Subnet groups
How can you add encryption to an unencrypted database instance? Create a DB snapshot
Encrypt the database snapshot using keys from KMS
Create a database from the encrypted snapshot
Are you billed if you stop your DB instance? You are billed for storage, IOPS, backups and snapshots. You are NOT billed for DB instance hours
I will need RDS for at least one year. How can I reduce costs? Use Amazon RDS reserved instances.
Efficiently manage database connections Use Amazon RDS Proxy
Sits between client applications (including lambdas) and RDS

Certification - Recommended Reading

Cloud Certifications - AWS, Azure and Google Cloud - Top 8 FAQ For Me

Google Cloud For Beginners - How to choose a Database Service?

Teaching Cloud Certifications - Top 6 Learnings

Google Cloud For Beginners - How to choose a Compute Service?

Important Kubernetes Concepts Made Easy

Introduction to Google Cloud - For AWS Professionals

Getting Started with Docker - 5 Easy Steps

GCP PubSub - GCP Certification Cheat Sheet

GCP IAM - GCP Certification Cheat Sheet

GCP App Engine - GCP Certification Cheat Sheet


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