The cloud promises flexibility, scalability and lower management costs. But a migration without a plan leads to unexpected costs, downtime and frustration. The difference between a smooth move and a painful one almost always comes down to preparation. Here is our proven five-phase plan, with the pitfalls we frequently see along the way.
Step 1: Map out your IT landscape
Before you move anything, you need to know exactly what you have. Take inventory of all your servers, applications, databases and their interdependencies. Ask three questions per system: how business-critical is it, how sensitive is the data, and what does it depend on to work?
That last question is often underestimated. Applications rarely stand alone: they talk to databases, external APIs, authentication services and each other. Move one application without mapping its dependencies, and you discover after the move that half of it no longer works. This baseline is the foundation for every decision that follows.
Step 2: Choose the right strategy per application
Not everything needs to move the same way. In practice we mainly use three strategies (the "R's"):
- Rehost ("lift-and-shift"): you move the application to the cloud unchanged. Fast and cheap, ideal as a first step or for systems that will be replaced soon anyway.
- Replatform: you make targeted optimizations — for example replacing a self-managed database with a managed service — without rewriting the application. A good balance between effort and gain.
- Refactor: you rebuild (parts of) the application to fully benefit from the cloud, for example with serverless or containers. The most work, but the biggest long-term gain.
A common mistake is forcing everything into one strategy. The reality is a mix: critical, fast-growing systems deserve a refactor; peripheral applications are fine with a lift-and-shift.
Step 3: Choose platform and architecture
AWS or Azure? That choice depends mostly on your existing software and your team's knowledge. But just as important is what you build afterwards: the foundation. Establish the basic principles early:
- Networking and segmentation: how are environments (test, production) separated?
- Access management: who may do what, following the principle of least privilege?
- Backup and recovery: what is your recovery objective if something goes wrong?
- Cost monitoring: who tracks consumption?
A well-designed base — a so-called "landing zone" — saves you a lot of headaches later. Adding governance afterwards is always more expensive than setting it up well from the start.
Step 4: Migrate in phases
Never migrate everything at once. Start with a non-critical application as a pilot. That first migration teaches you more about your own environment than any amount of planning. Test thoroughly — does the application work, are the performance and the backups in order? — and then roll out the rest step by step.
Where possible, work with a transition period in which old and new run side by side for a while. That lets you switch back if something goes wrong, and keeps your business running — ideally without noticeable downtime for your users.
Step 5: Optimize and manage
A migration isn't an endpoint, but a beginning. Once in the cloud, you continuously monitor both performance and costs. Switch off resources you don't need, match server sizes to actual load (rightsizing), scale automatically with demand, and keep your security up to date. This is where the real savings of the cloud are found — and it requires continuous follow-up, not a one-off action.
The biggest pitfall
The most common mistake? Moving an application to the cloud unchanged and expecting the bill to drop by itself. Without optimization, the cloud sometimes costs more than on-premise, because servers keep running 24/7 when they don't need to. The gain is in the right setup and follow-up — not in the move alone.
How long does a migration take?
There's no fixed answer: a simple lift-and-shift of a few applications can be done in weeks, while a full modernization of a complex landscape takes months. More important than speed is predictability: a phased plan with clear milestones gives you control over progress and costs at every moment.
Conclusion
A successful cloud migration is about preparation, not speed. With a clear plan — inventory, the right strategy per application, a solid foundation, phased rollout and continuous optimization — you avoid surprises and get the most out of AWS or Azure.
At Digitall.Expert, as an official AWS and Azure partner, we guide the entire journey — from baseline to management and optimization. Discover our cloud expertise or schedule a no-obligation conversation.