Moving to AWS: Migration Strategies for Beginners

The problem this concept solves

Imagine a small business still running its inventory system on an aging computer in a back office. The fan is loud, nobody remembers the original setup instructions, and the one person who understands it is about to retire. Moving that system to AWS sounds obviously better, but "just move it to the cloud" is not one action. Different applications need different approaches, and picking the wrong one can waste time or break something that used to work fine.

What it means in plain English

Migration means moving an application, its data, or its infrastructure from where it currently runs (often an on-premises data center, meaning physical servers a company owns and manages itself) to the cloud. Migration is not a single leap; it typically happens in phases:

• Assessment, where you figure out what you have and whether it is even worth moving.
• Mobilization, where you plan the details and prepare tools, accounts, and skills.
• Migration, where you actually move things, followed by testing, validation, and ongoing optimization once the workload is running on AWS.

Not every application deserves the same treatment. AWS describes seven common strategies for deciding what to do with each one.

The seven migration strategies

• Retire: Turn off an application that is no longer needed. Not everything old is worth moving.
• Retain: Leave an application where it is for now, often because it is not ready to move or there is no clear business reason yet.
• Rehost: Move an application to AWS with minimal changes, sometimes called "lift and shift." This is usually the fastest path.
• Relocate: Move infrastructure to AWS without redesigning the application, similar to rehosting but typically referring to moving an entire virtualized environment as a unit.
• Repurchase: Replace the existing application with a different product, often a cloud-based subscription service that does the same job.
• Replatform: Make a small number of cloud-focused optimizations during the move without a full redesign, sometimes called "lift, tinker, and shift."
• Refactor or re-architect: Redesign the application to take advantage of cloud-native capabilities, usually the most work but the most long-term flexibility.

A useful way to picture these: retire and retain are decisions about whether to move at all, rehost and relocate are quick moves with few changes, repurchase swaps the product entirely, and replatform and refactor involve improving the application, with refactor going the furthest.

Important AWS services and features

AWS Migration Hub gives you a central place to track migration status across multiple applications and tools, instead of checking several dashboards separately.

AWS Application Migration Service helps you rehost applications by replicating servers to AWS with minimal changes, fitting situations where speed matters more than an immediate redesign.

AWS Database Migration Service (AWS DMS) moves databases into AWS and can often keep the source database running during the migration, which matters when downtime is not an option.

AWS DataSync automates moving large amounts of data between on-premises storage and AWS storage services, useful for ongoing or scheduled transfers rather than a one-time database move.

The AWS Snow Family is a set of physical devices AWS ships to you for transferring very large amounts of data when the internet would take too long. Consider it when data volume, not database complexity, is the bottleneck.

The AWS Migration Acceleration Program (MAP) combines guidance, tools, and training to help organizations plan and execute larger migrations, supporting the assessment and mobilization phases, not just the technical move.

A practical example

Hypothetical scenario: A regional retailer runs its store-inventory application on an aging on-premises server and wants to modernize. Under time pressure, the team chooses to rehost it first using AWS Application Migration Service, moving it to AWS EC2 with minimal changes, while the database moves separately using AWS DMS to limit downtime. Once stable on AWS, the team plans a second phase: refactoring the inventory service into smaller, cloud-native components the following year, instead of redesigning everything before the initial move.

Do not confuse these concepts

• Rehost: Move with minimal changes, fastest but keeps existing limitations.
• Replatform: Move with a few cloud optimizations, more effort than rehosting but not a full redesign.
• Refactor or re-architect: Redesign for cloud-native capabilities, most effort but most long-term benefit.
• Retire vs. Retain: Retire removes an application permanently; retain keeps it running as-is with no move planned yet.

Cloud Practitioner exam connection

The exam expects you to recognize which of the seven strategies fits a short scenario description, rather than list every detail of each migration tool. Pay attention to keywords: "minimal changes" usually signals rehost, "redesign" usually signals refactor, and "replace with a different product" signals repurchase. You should also be able to distinguish AWS DMS (for databases) from AWS DataSync (for general file and storage transfers) and recognize the Snow Family as the answer when a scenario describes extremely large data volumes and limited network bandwidth.

Quick recall

Strategy	In one line	Keyword that gives it away
Retire	Turn it off	"no longer needed," "decommission"
Retain	Leave it alone for now	"not ready," "revisit later," "keep on premises"
Rehost	Move as-is	"lift and shift," "minimal changes," "as quickly as possible"
Relocate	Move the whole virtualized environment	"move VMware without changing the app"
Repurchase	Buy a different product instead	"replace with SaaS," "move to a subscription product"
Replatform	Small cloud optimizations during the move	"lift, tinker, and shift," "a few improvements"
Refactor	Redesign for cloud-native	"re-architect," "microservices," "take full advantage of the cloud"

Tool	Use it for
AWS Migration Hub	One dashboard tracking migration progress
AWS Application Migration Service	Rehosting servers with minimal change
AWS DMS	Migrating databases with little downtime
AWS DataSync	Moving files and object data over the network
AWS Snow Family	Very large data volumes where the network is too slow
AWS Application Discovery Service	Inventorying on-premises servers during assessment

The AWS Cloud Adoption Framework (CAF) organizes migration readiness into six perspectives: Business, People, Governance, Platform, Security, and Operations. The first three are business-focused; the last three are technical.

Key takeaways

• Migration happens in phases (assessment, mobilization, migration and beyond) and is not a single action.
• The seven migration strategies, from least to most redesign, are retire, retain, rehost, relocate, repurchase, replatform, and refactor.
• AWS Migration Hub, Application Migration Service, DMS, DataSync, and the Snow Family each support a different part of the migration journey, from tracking progress to moving specific types of data.

Check your understanding

1. A company wants to move an application to AWS as quickly as possible with the fewest changes. Which migration strategy fits best?
2. What is the difference between AWS Database Migration Service and AWS DataSync?
3. Why might a company choose the Snow Family instead of transferring data over the internet?

Suggested answers

1. Rehost, because it moves the application with minimal changes and is generally the fastest strategy.
2. AWS DMS is designed specifically for migrating databases, often while keeping the source database available, while AWS DataSync automates moving files and other data between on-premises storage and AWS storage services.
3. The Snow Family is useful when the amount of data is so large that transferring it over the internet would take too long or cost too much, making a physical device a faster option.

Continue learning

• AWS migration strategies overview
• AWS Database Migration Service documentation