Many companies are moving their old on-premises data centers to AWS. But not every system can be moved the same way. Some need to be moved quickly, others need a fresh design, and some might not even be worth keeping.
This article explains the 6 migration strategies (6Rs) and the key tools you need to know for the exam — explained in plain, everyday language.
---
Think of It Like Moving Offices
Imagine your company is moving from an old office building to a brand new one. What do you do with all the furniture and equipment?
Some things you move as-is (Rehost). Some you adjust slightly to fit the new space (Replatform). Some you replace with brand new items (Repurchase). Some you redesign from scratch for the new space (Refactor). Some you realize you no longer need and throw away (Retire). And some you decide to leave in the old office for now (Retain).
That is exactly the 6R framework.
---
Rehost — Move It As-Is
Also called "Lift and Shift." You move the server to the cloud without changing a single line of code.
This is the fastest approach, but you do not fully take advantage of cloud features. AWS Application Migration Service (MGN) automates this process.
---
Replatform — Move It with Minor Improvements
Also called "Lift, Tinker, and Shift." You keep the core structure but swap in a cloud-managed service to reduce your maintenance work.
For example, instead of managing your own MySQL database on a virtual machine, you move it to Amazon RDS. AWS then handles OS patches, backups, and database engine updates for you.
---
Refactor — Redesign from the Ground Up
Also called "Re-architecting." You redesign the application to fully take advantage of cloud-native features like serverless, auto-scaling, and managed services.
This takes the most time and money upfront but delivers the greatest long-term benefits. Think of it as custom-building new furniture that perfectly fits the new office.
---
Repurchase — Replace with a SaaS Product
You stop using your old custom-built software and switch to a ready-made cloud service. For example, replacing a self-hosted CRM system with Salesforce.
No more maintenance burden — you just use the finished product.
---
Retire — Decommission What You No Longer Need
During a migration assessment, companies often discover systems that nobody uses anymore. Simply turning those off saves money immediately.
---
Retain — Leave It for Now
Some systems are not ready to move yet. It is smarter to leave them in place temporarily than to rush and cause problems. You can always migrate them later.
!The 6 Rs of cloud migration strategy
Key Migration Tools
| Tool | What It Does | |------|-------------| | AWS Migration Hub | Tracks the entire migration from one central view | | AWS MGN | Rehost (lift-and-shift) servers with no code changes | | AWS DMS | Migrates databases to AWS even while they are running | | AWS SCT | Converts database schemas from one engine format to another | | AWS Snow Family | Moves massive amounts of data via physical devices shipped to AWS |
Snow Family is especially important to know. If you have dozens of terabytes of data, transferring it over the internet could take months. Snow Family devices let you copy the data locally and ship the physical device to AWS.
Snowcone: Up to 8 TB, small enough to fit in a bag Snowball Edge: Up to 80 TB, can also run simple compute jobs on-site Snowmobile: Up to 100 PB, a truck-sized shipping container
---
AWS Cloud Adoption Framework (CAF)
CAF is a framework that helps organizations plan their cloud adoption systematically. It looks at readiness across 6 perspectives: Business, People, Governance, Platform, Security, and Operations — not just the technical side.
---
Exam Key Points
"Move with no code changes" -- Rehost (Lift-and-Shift)
"Move with some cloud optimizations" -- Replatform
"Redesign from scratch for cloud-native" -- Refactor
"Replace with a cloud SaaS product" -- Repurchase
"Turn off unneeded systems" -- Retire
"Not moving yet" -- Retain
"Move large data volumes physically when internet transfer is impractical" -- Snow Family
"Migrate a running database to AWS" -- AWS DMS
"Track the entire migration from one place" -- Migration Hub
Snow Family size order: Snowcone (8 TB) < Snowball Edge (80 TB) < Snowmobile (100 PB)