Lift-and-shift versus replatforming migration
knowledge of the migration 6 Rs.
rehosting moves apps unchanged for speed and low risk; replatforming makes targeted optimizations for cloud benefits; explain the speed-versus-value trade-off.
WHAT THIS TESTS This checks familiarity with the migration 6 Rs and the core trade-off between migration speed and the depth of cloud value captured.
A GOOD ANSWER COVERS Rehosting, or lift and shift, moves an application to the cloud essentially unchanged, often as VMs. Pros: fastest, lowest engineering effort and risk, good for tight deadlines, data-center exits, or migrating many apps quickly; it can be partly automated. Cons: it carries existing inefficiencies along, does not exploit managed or elastic services, and frequently fails to lower cost on its own. Replatforming, sometimes called lift-tinker-and-shift, makes a few targeted changes during migration, such as moving from a self-managed database to a managed service or containerizing, to gain real cloud benefits without a full rewrite. Pros: better cost and operational gains. Cons: more effort, testing, and risk than rehosting.
COMMON WRONG ANSWERS Equating lift-and-shift with refactoring or re-architecting. Claiming rehosting automatically saves money. Saying replatforming means rewriting the application. Ignoring that the choice depends on timeline, risk tolerance, and business value.
LIKELY FOLLOW-UPS What are the other Rs? When would you refactor instead? How do you decide per application? What hidden costs follow a pure lift-and-shift?
ONE CONCRETE EXAMPLE A company exiting its data center in six months rehosts a hundred legacy apps as EC2 VMs to hit the deadline. For its busiest app, it replatforms by moving the self-managed MySQL onto RDS, gaining automated backups, patching, and failover, while leaving the application code mostly untouched, a measured step up in value for modest added effort.
Interview question
What is the primary trade-off when choosing rehosting over replatforming for a migration?
- a.Rehosting is slower but always cheaper to operate afterward
- b.Replatforming eliminates all need for testing
- c.Rehosting is faster and lower-risk but captures fewer cloud-native benefitsCorrect
- d.Rehosting requires rewriting the application from scratch
Why? this is the answer
Lift-and-shift wins on speed and risk but inherits old inefficiencies and skips managed services. It does not require a rewrite, is not guaranteed to be cheaper to run, and replatforming still demands testing.
Just read this? Test yourself on what you have been reading.
Read the original → docs.aws.amazon.com
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- #lift-and-shift
- #replatforming
- #strategy
- #fundamentals
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