AWS, Azure & GCP · Cloud across providers
What are the main cloud migration strategies?
Short answer
The common 6 Rs are rehost, replatform, refactor, repurchase, retire and retain. Most migrations start with discovery and portfolio assessment, then move low-risk workloads first and modernise where justified.
Migration is a portfolio problem, not a single application decision. Different workloads need different strategies depending on business value, technical debt, dependencies and risk tolerance.
The 6 Rs
- Rehost: lift and shift to virtual machines, fast but carries existing problems
- Replatform: move with targeted changes, such as a managed database, without a full rewrite
- Refactor: redesign for cloud-native services, highest effort and highest long-term benefit
- Repurchase: replace with a SaaS product, shifting build and operations to a vendor
- Retire: decommission workloads that are no longer needed
- Retain: keep on-premises for now because of latency, licensing or compliance
Sequence matters. Start with discovery, dependency mapping and a landing zone that provides identity, networking, logging, guardrails and cost controls. Migrate a small, low-risk workload first to validate the operating model, then increase complexity.
Risks to plan for
- Hidden dependencies and undocumented integrations
- Data transfer time and egress cost
- Licensing and support changes
- Cutover downtime and rollback plans
- Skills gaps in the receiving platform
- Cost surprises after the initial migration discount ends
Follow-ups you should expect
Interviewers use these to check whether the first answer was understanding or memorisation.
- 1How do you choose between rehost and replatform for a given workload?
- 2Why build a landing zone before migrating workloads?
- 3How do you handle dependencies during cutover?
- 4How do you avoid cost surprises after migration?
Say it in the interview
I treat migration as a portfolio decision using the 6 Rs: rehost, replatform, refactor, repurchase, retire and retain. I start with discovery and a landing zone for identity, network, logging and guardrails, then move a low-risk workload first to prove the operating model. Lift and shift can be a valid first step, but I plan the modernisation path so we do not carry the old estate's cost and fragility forward.
Use this as a model, not a script. Saying it in your own words is what makes it survive follow-up pressure.
Related questions
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