CLF-C02
Deep Dive
Migrating to AWS isn't just moving servers — it's a business transformation. Understand the benefits of the AWS Cloud Adoption Framework (CAF), the 7 migration strategies, and the tools AWS offers to plan and execute the migration.
According to the AWS Cloud Adoption Framework (CAF), migrating to the cloud delivers four broad categories of business benefits.
Reduced business risk
Greater resilience, faster disaster recovery, security managed by AWS, compliance with global standards. Reduces exposure to hardware failures and cyberattacks.
Improved ESG (Environmental, Social, Governance)
Lower carbon footprint by consolidating infrastructure in AWS's high-efficiency data centers. AWS runs on renewable energy. Reduces your own power consumption.
Increased revenue
Faster launches of products and features, global expansion in minutes, the ability to experiment and innovate without upfront hardware investment.
Operational efficiency
Automation of manual tasks, elimination of hardware maintenance, IT teams redirected to higher-value differentiating projects instead of infrastructure management.
AWS defines 7 migration strategies (the "7 R's") for moving workloads to the cloud. Each application may require a different strategy depending on its architecture, business value, and tolerance for change.
Identify applications that are no longer needed and remove them. There's no point migrating what isn't used.
When to use
Obsolete applications, legacy systems nobody currently uses, functional duplicates.
Effort
None
Example
A legacy reporting system replaced by a modern SaaS solution.
Keep applications on-premises for now. This may be due to technical dependencies, regulation, or lack of urgency.
When to use
Apps that were recently refreshed, strict regulatory requirements, no business case to migrate yet.
Effort
None
Example
An Oracle database with a maintenance contract still valid for 2 more years.
Move the application to AWS as-is, without changing the architecture or the code. The same app, on EC2 instead of your own servers.
When to use
Fast migration, minimizing change risk, the initial phase of a large-scale migration.
Effort
Low
Example
An on-premises Apache web server + MySQL moved to EC2 + RDS with no changes.
Make minor optimizations to take advantage of the cloud without changing the core architecture. No code rewrite, just tweaks.
When to use
You want to cut management costs without rewriting. You can accept some configuration optimizations.
Effort
Medium
Example
Migrating an on-premises MySQL database to Amazon RDS (same app, AWS manages the OS and patching).
Replace the application with a different product, typically SaaS. Abandon the current version and adopt a cloud-native product.
When to use
The vendor has a superior SaaS version, the current app is costly to maintain.
Effort
Low to medium (SaaS configuration)
Example
Replacing an on-premises CRM system with Salesforce or HubSpot.
Reimagine how the application is designed using cloud-native features. Deep architectural changes for better performance, scale, or maintainability.
When to use
The app has urgent scale/performance needs it can't meet in its current state.
Effort
High
Example
A Java monolith migrated to microservices on AWS Lambda + API Gateway + DynamoDB.
Move infrastructure to AWS at the hypervisor level, without buying new hardware. Specific to VMware-to-AWS migrations (VMware Cloud on AWS).
When to use
A VMware environment you want to migrate en masse to AWS without rewriting anything.
Effort
Low (automated at the hypervisor level)
Example
Moving 500 VMs from on-premises VMware to VMware Cloud on AWS in days.
For the exam — Common trap
Rehost = pure lift-and-shift. No changes. Just moves the VM to EC2.
Replatform = lift-tinker-and-shift. A small optimization (e.g. moving to RDS). No rewrite.
Refactor = deep rewrite. Microservices, serverless, cloud-native.
Repurchase = switch to a SaaS. You're not migrating the app — you're replacing it.
The AWS CAF provides guidance and best practices to help organizations develop an efficient plan for cloud adoption. It defines 6 perspectives that cover every aspect of a successful migration.
Business
Perspective: Business
Aligns migration with business objectives. Defines the business case and the ROI of the cloud. Stakeholders: executives, business leaders.
People
Perspective: People
Organizational change management. Team training, new role structures, cloud-first culture. Stakeholders: HR, people leaders.
Governance
Perspective: Governance
Management controls, cloud usage policies, risk management and compliance. Stakeholders: CIO, program managers, enterprise architects.
Platform
Perspective: Platform
Architecture principles, design of the target platform on AWS, technical migration patterns. Stakeholders: CTO, solutions architects.
Security
Perspective: Security
Shared responsibility model, security controls, data classification, identity management. Stakeholders: CISO, security teams.
Operations
Perspective: Operations
Operational processes, monitoring, event management, business continuity. Stakeholders: IT operations, site reliability engineers.
CAF and the 7 R's together
CAF defines organizational readiness (culture, people, governance) while the 7 R's define the technical strategy for each individual application. In a real migration: first CAF to assess maturity, then the 7 R's to plan each workload.
AWS offers a full set of tools for every phase of migration: discovery, planning, execution, and tracking.
AWS Application Discovery Service
DiscoveryCollects information about on-premises infrastructure before migrating. Discovers servers, application dependencies, and CPU/memory/network usage. Generates an automatic inventory to plan the migration. Since November 2025 it no longer accepts new customers; its successor is AWS Transform.
For the exam
When the scenario mentions "on-premises inventory" or "discover what's in the data center," the answer is Application Discovery Service.
AWS Application Migration Service
ExecutionThe primary automated lift-and-shift service (formerly CloudEndure Migration). Replicates physical, virtual, or cloud-based servers to AWS in real time with minimal downtime.
For the exam
For automatically migrating physical servers or VMs to AWS (Rehost/lift-and-shift).
AWS Migration Hub
TrackingProvides a centralized location for tracking the progress of application migrations. Consolidates the status of all migrations in a single dashboard, regardless of which tool is being used. Since November 2025 it no longer accepts new customers; its successor is AWS Transform.
For the exam
Centralizing and monitoring the status of a large-scale migration across multiple tools.
AWS Migration Evaluator
PlanningAnalyzes current on-premises usage and generates a business case with the TCO (Total Cost of Ownership) comparing on-premises vs AWS. Formerly known as TSO Logic.
For the exam
When the scenario asks to "justify the migration with cost data" or "build a business case for migration."
AWS Database Migration Service (DMS)
Data migrationMigrates databases to AWS with minimal downtime. Supports homogeneous migrations (MySQL → RDS MySQL) and heterogeneous ones (Oracle → Aurora PostgreSQL). The source database stays operational during the migration.
For the exam
Migrating a database to AWS with minimal downtime. Always DMS for data in motion.
AWS Schema Conversion Tool (SCT)
Data migrationAutomatically converts the database schema from one engine to another (Oracle → PostgreSQL, SQL Server → Aurora). Also converts stored-procedure code.
For the exam
SCT converts the SCHEMA. DMS migrates the DATA. They're used together for heterogeneous migrations.
AWS Snow Family
Bulk data migrationPhysical devices for migrating large volumes of data when internet bandwidth isn't sufficient. Snowcone (8 TB) and Snowmobile (100 PB) are already retired, and Snowball Edge (80 TB) has not accepted new customers since November 2025: AWS now recommends DataSync or Data Transfer Terminal.
For the exam
When there are petabytes of data and the network transfer would take months: Snow Family. Rule of thumb: if it would take more than 1 week over the network → Snow.
Real costs of on-premises
Many companies underestimate the total cost
Rightsizing — Matching actual usage
On-premises, you provision for peak load (using only 15-30% of average capacity). On AWS you pay for what you use. Rightsizing = analyzing actual instance usage and adjusting the instance type to the minimum needed without degrading performance.
BYOL vs license-included
BYOL (Bring Your Own License): bring your existing Windows/SQL Server license to AWS (on Dedicated Hosts or EC2).License-included: AWS includes the license in the price (e.g. RDS for SQL Server, Windows AMIs). Evaluate which is more economical given your current contracts.
Benefits of automation
AWS lets you automate tasks that previously required staff: OS patching (Systems Manager), backups (AWS Backup), scaling (Auto Scaling), deployments (CloudFormation). This removes repetitive manual work and reduces human error.
| Dimension | On-premises (Fixed costs) | AWS Cloud (Variable costs) |
|---|---|---|
| Upfront investment | High — hardware before you use it | Zero — pay once you start using it |
| Capacity | Over-provision for peaks (underutilized) | Elasticity: adjusts in minutes based on demand |
| Infrastructure staff | Own team for hardware, network, data center | AWS manages the physical infra; your team focuses on value |
| Time to market | Weeks to provision new hardware | Minutes to provision any resource |
| Global scale | Contracts, data centers, months of work | Deploy to a new region in minutes |
| Cost type | CapEx (fixed assets that depreciate) | OpEx (variable operating expense) |
Did you get this topic?
Test what you just learned
A retail company wants to migrate its inventory management system to AWS. The technical team wants to minimize changes to the application's code and architecture, but is willing to switch from an on-premises MySQL database to Amazon RDS (without modifying the application code). Which migration strategy best describes this situation?
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