Skip to content

CLF-C02 Study Notes: Migration to AWS Cloud

Task Statement 1.3

You should understand:

  • Benefits of migrating to AWS
  • AWS Cloud Adoption Framework (AWS CAF)
  • Cloud adoption stages
  • The seven migration strategies
  • AWS services that support migration
  • Selecting appropriate AWS storage and database services
  • Storage costs, retrieval fees, and retrieval times

Benefits of Migrating to AWS

Migrating workloads to AWS can help organizations:

  • Reduce business risk through improved reliability
  • Improve application performance
  • Enhance security
  • Increase operational efficiency
  • Reduce infrastructure and operating costs
  • Increase employee productivity
  • Create new products and services
  • Reach new customers and markets
  • Improve sustainability and transparency

The specific benefits depend on the migration strategy and the AWS services selected.

AWS Cloud Adoption Framework

What Is AWS CAF?

The AWS Cloud Adoption Framework (AWS CAF) provides guidance for organizations planning and managing a cloud transformation.

It helps an organization:

  • Assess its cloud readiness
  • Identify gaps in organizational capabilities
  • Identify and prioritize transformation opportunities
  • Reduce risks during cloud adoption
  • Create and improve a cloud transformation roadmap
  • Establish the people, processes, and technology needed for successful adoption

Exam distinction: AWS CAF focuses on organizational transformation and cloud adoption. The AWS Well-Architected Framework focuses on designing and operating reliable, secure, efficient, and cost-effective workloads.

Six AWS CAF Perspectives

AWS CAF capabilities are organized into six perspectives:

Perspective Main focus
Business Business strategy, value, outcomes, and business cases
People Skills, roles, organizational change, and culture
Governance Policies, risk management, compliance, and portfolio management
Platform Cloud infrastructure, architecture, and technology
Security Security controls, identity, compliance, and risk
Operations Operating processes, monitoring, service management, and business continuity

How to Use AWS CAF

An organization can use AWS CAF to:

  1. Assess its current cloud readiness.
  2. Identify capability gaps.
  3. Prioritize transformation opportunities.
  4. Create a migration and transformation roadmap.
  5. Iteratively improve its cloud adoption approach.

Cloud Adoption Stages

Organizations may progress through several stages as they adopt AWS.

1. Project Stage

The organization is evaluating whether AWS meets its requirements.

Typical activities include:

  • Running proofs of concept
  • Evaluating technical feasibility
  • Determining whether AWS can meet business and application needs

2. Foundation Stage

The organization begins migrating to AWS.

Examples include:

  • Moving a few production applications to AWS
  • Deploying an initial landing zone
  • Deploying an initial AWS environment for non-production workloads

3. Migration Stage

The organization begins preparing for long-term cloud operations.

Activities may include:

  • Defining cloud operations roles
  • Establishing a Cloud Center of Excellence (CCoE)
  • Developing cloud governance and operating procedures
  • Moving from on-premises operations to cloud operations

4. Reinvention Stage

AWS becomes the default platform for new projects.

Examples include:

  • Starting all new applications in AWS
  • Building cloud-native applications
  • Using AWS capabilities to improve agility, scalability, and performance

Exam tip: Identify the stage based on the organization’s behavior. A company evaluating AWS is in the project stage; a company starting migrations is in the foundation stage; a company creating formal cloud operations and a CCoE is in the migration stage.

The Seven Migration Strategies

The seven migration strategies are commonly called the 7 Rs.

Strategy Also known as Description
Retire — Decommission applications that are no longer needed
Retain — Keep applications in the source environment because they are not ready or suitable to migrate
Rehost Lift and shift Move an application to AWS without changing its architecture or code
Relocate — Move large groups of servers or one or more applications to AWS, often with minimal changes
Repurchase Drop and shop Replace an existing application with a different product or version, often by purchasing a cloud-based solution
Replatform Lift, tinker, and shift Make limited optimizations while keeping the core architecture largely unchanged
Refactor Re-architect Redesign an application to take full advantage of cloud-native capabilities

Understanding the Differences

Rehost

Use rehosting when:

  • You need to migrate quickly
  • You want minimal application changes
  • The application can run in AWS with its existing architecture

Example: Move an on-premises virtual machine to Amazon EC2 without changing the application.

Relocate

Use relocation when:

  • Moving a large number of servers
  • Moving one or more complete applications
  • The migration requires moving the environment as a whole

Repurchase

Use repurchasing when:

  • Replacing an existing system with a different product
  • Adopting a software-as-a-service solution
  • A new product provides more value than maintaining the current infrastructure

Replatform

Use replatforming when:

  • The application needs some optimization
  • You want to use selected AWS capabilities
  • You do not want to completely redesign the application

Example: Move a database to Amazon RDS while making minimal application changes.

Refactor

Use refactoring when:

  • You want to redesign the application
  • You want maximum agility, scalability, or performance
  • You want to take full advantage of cloud-native services

Exam trap:
- Rehost means no significant application changes.
- Replatform means some optimization.
- Refactor means substantial redesign or re-architecture.
- Retire means decommission.
- Retain means leave the workload where it is.

AWS Services That Support Migration

AWS Database Migration Service

AWS Database Migration Service (AWS DMS) helps migrate databases to AWS.

It can be used for:

  • Migrating databases to AWS
  • Migrating between different database engines in some scenarios
  • Replicating data while the source database remains in use
  • Supporting migrations where the database is frequently changing

Exam clue: If the question mentions database replication, continuous data replication, or migrating a database while minimizing downtime, consider AWS DMS.

AWS Snowball Edge

AWS Snowball Edge is a physical device used to transfer large amounts of data into or out of AWS.

Use it when:

  • Network transfer would take too long
  • The organization has large volumes of data
  • Data must be transferred physically
  • Connectivity is limited or unreliable

Exam trap: Snowball Edge is for large-scale data transfer. It is not normally the best answer for an application requiring continuous, low-latency access to data.

Choosing AWS Storage and Database Services

Amazon Elastic File System

Amazon EFS is a managed, elastic file system that can be mounted by Amazon EC2 instances.

Use EFS when you need:

  • Shared file storage
  • File-based storage for multiple EC2 instances
  • Storage capacity that grows and shrinks automatically
  • Low-latency access from resources in the VPC

Typical use cases include:

  • Shared application files
  • Content management systems
  • Web serving
  • File-based workloads

Amazon S3

Amazon S3 is object storage.

Use S3 for:

  • Backups
  • Archives
  • Data lakes
  • Static website content
  • Media and other unstructured data
  • Highly durable object storage

S3 is not a traditional file system or relational database.

Exam tip: S3 is often a good general-purpose storage answer, but do not select it when the question specifically requires a shared file system with low-latency access from EC2 instances.

Amazon RDS

Amazon Relational Database Service (Amazon RDS) is a managed relational database service.

Use RDS when you need:

  • A relational database
  • SQL-based workloads
  • Managed backups and maintenance
  • High availability options
  • Support for common database engines, including Microsoft SQL Server

RDS reduces the administrative work required to manage database infrastructure.

Amazon Aurora

Amazon Aurora is a managed relational database engine compatible with:

  • MySQL
  • PostgreSQL

Exam trap: Amazon Aurora does not run Microsoft SQL Server. For SQL Server workloads, consider Amazon RDS for SQL Server or Amazon EC2 with SQL Server.

Amazon DynamoDB

Amazon DynamoDB is a fully managed NoSQL database.

Use DynamoDB when you need:

  • A key-value database
  • A document database
  • Fast and predictable performance
  • Automatic scalability
  • A highly available managed database
  • JSON-like document storage

Exam clue:
- NoSQL, key-value, or document database → Amazon DynamoDB
- Relational, SQL, or tables with relationships → Amazon RDS or Amazon Aurora

Amazon EC2 with a SQL Server AMI

Amazon EC2 can run Microsoft SQL Server using an appropriate Amazon Machine Image (AMI).

For example, an EC2 Windows AMI may include:

  • Windows Server
  • SQL Server Standard

This option may be more cost-effective than Amazon RDS when:

  • The question emphasizes minimizing cost
  • You need SQL Server Standard
  • You are willing to manage the operating system and database
  • A bundled license is appropriate

RDS Versus EC2 for SQL Server

Option Advantages Considerations
Amazon RDS for SQL Server Managed database, automated maintenance and backups Usually costs more; less infrastructure administration
Amazon EC2 with SQL Server AMI More control and potentially lower cost You manage the operating system and database

Exam trap: Managed services often reduce administrative effort but may cost more than managing equivalent infrastructure yourself.

Storage Classes and Data Backups

A migration plan should include a strategy for storing and protecting data after migration.

Amazon S3 Glacier Storage Classes

S3 Glacier storage classes are designed for low-cost archival storage.

Use them for:

  • Long-term backups
  • Compliance archives
  • Infrequently accessed data
  • Data that does not require immediate access

Important considerations include:

  • Storage costs are low
  • Retrieval fees may apply
  • Retrieval can take longer than standard S3 storage classes
  • The appropriate class depends on how quickly data must be retrieved

Exam tip: The lowest storage price is not always the lowest total cost. Consider both storage costs and data retrieval requirements.

Common Service Comparisons

Requirement Appropriate AWS service
Shared, elastic file storage for EC2 Amazon EFS
Object storage and backups Amazon S3
Large-scale physical data transfer AWS Snowball Edge
Database replication during migration AWS DMS
Managed relational database Amazon RDS
Managed MySQL- or PostgreSQL-compatible relational database Amazon Aurora
Managed NoSQL key-value or document database Amazon DynamoDB
Maximum control over SQL Server infrastructure Amazon EC2
Low-cost long-term archival storage S3 Glacier storage classes

Exam Tips and Traps

  • Do not confuse AWS CAF with the AWS Well-Architected Framework.
  • CAF: organizational cloud adoption and transformation.
  • Well-Architected: workload architecture and operational best practices.

  • Memorize the six CAF perspectives: Business, People, Governance, Platform, Security, Operations.

  • Memorize the seven migration strategies: Retire, Retain, Rehost, Relocate, Repurchase, Replatform, Refactor.

  • “Lift and shift” means rehost.

  • “Lift, tinker, and shift” means replatform.
  • “Redesign to fully use cloud-native features” means refactor.
  • “No longer needed” means retire.
  • “Not ready to migrate” means retain.
  • Select AWS DMS for database migration and replication.
  • Select Snowball Edge for very large data transfers when network transfer is impractical.
  • Select DynamoDB for NoSQL workloads.
  • Select RDS for managed relational databases.
  • Aurora supports MySQL and PostgreSQL compatibility, not Microsoft SQL Server.
  • Choose EC2 over RDS when the question emphasizes lower cost and accepts the responsibility of managing the database.
  • For archival storage, account for both retrieval cost and retrieval time.

Practice Questions

Question 1

A company wants to evaluate whether AWS can meet the technical and business requirements of its applications before beginning a migration. Which AWS CAF adoption stage best describes this activity?

A. Foundation
B. Migration
C. Project
D. Reinvention

Answer: C. Project

Explanation: The project stage involves evaluating whether migrating to AWS meets the organization’s requirements.

Question 2

Which AWS Cloud Adoption Framework perspective focuses primarily on organizational roles, skills, and change management?

A. Security
B. People
C. Platform
D. Governance

Answer: B. People

Explanation: The People perspective addresses skills, roles, organizational change, and culture.

Question 3

A company wants to move an application to Amazon EC2 without modifying the application code or architecture. Which migration strategy should it use?

A. Rehost
B. Replatform
C. Refactor
D. Repurchase

Answer: A. Rehost

Explanation: Rehosting, also called lift and shift, moves an application without significant changes.

Question 4

A company wants to migrate a database to AWS while the source database remains online and continues to receive updates. Which AWS service can provide data replication during the migration?

A. Amazon S3
B. AWS Database Migration Service
C. AWS Snowball Edge
D. Amazon EFS

Answer: B. AWS Database Migration Service

Explanation: AWS DMS supports database migration and ongoing data replication, helping reduce downtime.

Question 5

A company needs shared, elastic file storage that can be accessed by multiple Amazon EC2 instances. Which service should it use?

A. Amazon S3
B. Amazon DynamoDB
C. Amazon EFS
D. AWS Snowball Edge

Answer: C. Amazon EFS

Explanation: Amazon EFS provides elastic, managed file storage that can be mounted by EC2 instances.

Question 6

A company is migrating a non-relational database. The database must provide fast, predictable performance and automatic scalability. Which service is most appropriate?

A. Amazon RDS
B. Amazon DynamoDB
C. Amazon Redshift
D. Amazon S3

Answer: B. Amazon DynamoDB

Explanation: DynamoDB is a fully managed NoSQL key-value and document database designed for scalable performance.

Question 7

A company needs to run Microsoft SQL Server Standard in AWS. Cost optimization is important, and the company is willing to manage the operating system and database. Which option may be the most cost-effective?

A. Amazon Aurora
B. Amazon RDS for SQL Server
C. Amazon EC2 with a Windows AMI that includes SQL Server Standard
D. Amazon DynamoDB

Answer: C. Amazon EC2 with a Windows AMI that includes SQL Server Standard

Explanation: Aurora does not support SQL Server. RDS is managed but can cost more. An EC2 AMI with SQL Server Standard may reduce cost, although the company must manage more of the environment.

Question 8

A company needs to transfer a very large amount of data to AWS, but its network connection would require several months to complete the transfer. Which service should it consider?

A. AWS Snowball Edge
B. Amazon DynamoDB
C. Amazon RDS
D. Amazon EFS

Answer: A. AWS Snowball Edge

Explanation: Snowball Edge uses physical devices to transfer large amounts of data when network transfer is too slow or impractical.

Question 9

A company wants to completely redesign an application to use cloud-native services and improve scalability and agility. Which migration strategy should it choose?

A. Retain
B. Rehost
C. Replatform
D. Refactor

Answer: D. Refactor

Explanation: Refactoring, or re-architecting, involves substantially redesigning an application to take full advantage of cloud-native capabilities.

Question 10

A company stores compliance backups that are rarely accessed. It wants the lowest possible storage cost but understands that retrieval may take longer and incur additional fees. Which option is appropriate?

A. Amazon S3 Glacier storage classes
B. Amazon EFS
C. Amazon DynamoDB
D. Amazon EC2 instance storage

Answer: A. Amazon S3 Glacier storage classes

Explanation: S3 Glacier storage classes are designed for low-cost archival storage, but retrieval fees and retrieval times must be considered.