The decision to move to the cloud is rarely the hard part. The hard part is everything that comes after. A cloud migration isn't a weekend project. It's an operation that affects your infrastructure, your processes, and sometimes your entire organisation.
The good news: it's not black magic. Cloud migration is a field with proven methodologies, known pitfalls, and measurable results. The organisations that succeed have one thing in common: they start with strategy, not technology.
Why do companies migrate to the cloud?
The reasons aren't the same for every organisation, but a few patterns keep recurring.
Aging hardware is the most pragmatic reason. Servers have a lifespan of three to five years. At some point the choice becomes: invest again in your own hardware, or shift the problem to a party that does it better. The cloud turns a one-time capital investment into an ongoing operational expense. Whether that works out cheaper depends on your situation, but it's certainly more predictable.
Scalability is the second driver. A webshop that gets five times more visitors at Christmas doesn't want to pay for five times the server capacity all year. Cloud makes it possible to scale up and down based on actual demand. That's the theory anyway. In practice, it requires an architecture designed for that.
The third reason is operational burden. Running your own servers means managing them yourself: patching, monitoring, backups, security, physical maintenance. Managed cloud hosting shifts that to a provider who does it as their core activity. Your IT team can focus on what adds value to your organisation instead of keeping things running.
And then there's regulation. The Cybersecurity Act (NIS2 implementation, expected Q2 2026) sets requirements for risk management, incident reporting, and supply chain security. For organisations with outdated on-premise infrastructure, migrating to a compliant cloud platform may be the fastest route to compliance.
The 7 R's: which strategy fits your application?
Not every application is migrated the same way. The 7R framework, originally developed by Gartner and later expanded by AWS, gives you seven strategies to choose from per application:
Rehost (lift-and-shift): you move the application to the cloud without modifications. Fast, low risk, but you don't fully leverage the cloud's benefits. Suitable as a first step or for applications that will be replaced soon.
Relocate: you move your infrastructure to a different platform without changing the application. Think of moving VMware workloads to a cloud-based virtualisation environment.
Replatform (lift-and-optimize): you adjust the application on a few points to better use cloud services. For example: moving your database to a managed database service, but leaving the application itself unchanged.
Refactor (re-architect): you rewrite the application to become cloud-native. Containerisation, microservices, serverless. This costs the most but delivers the greatest flexibility and scalability in the long run.
Repurchase: you replace the application with a SaaS service. Your own CRM to Salesforce, your own email server to Microsoft 365. You're not migrating the application, you're replacing the concept.
Retain: you keep the application where it is. Not everything belongs in the cloud. Some applications are too complex to migrate, too old to refactor, or too critical to touch right now. Deliberately retaining is also a strategy.
Retire: you shut the application down. It sounds simple, but in practice organisations run dozens of systems that nobody knows the purpose of anymore. A migration is a good moment to clean up.
The 7 R's of cloud migration
From low to high: effort and cloud benefit
Source: Gartner (2011), expanded by AWS · Choose per application, not the same approach for everything
Phase 1: Discovery and assessment
Before you move anything, you need to know what you have. That sounds obvious, but most organisations underestimate the scope of their own IT landscape. There are servers nobody owns anymore. Databases with undocumented structures. Integrations that only work because someone wrote a script five years ago that hasn't been touched since.
A discovery phase maps everything: which applications run, on which servers, with which dependencies. How much compute and storage do they use? What data do they process, and what compliance requirements come with that? Who owns it? What does it cost now, and what would it cost in the cloud?
This is also the moment to choose the migration strategy per application using the 7R framework. Some systems are simple to move. Others need to be rewritten. And some you might be able to shut down.
Phase 2: Planning and architecture
With the inventory on the table, you can start planning. The question isn't just "how do we move this" but also "how do we want it to look afterwards". A migration is an opportunity to pay off technical debt. It's also the time to think about your cloud architecture: public, private or hybrid? One provider or multiple? Which services managed, which self-run?
The planning phase produces a migration schedule: which applications when, in what order, with what rollback strategy if things go wrong. The order isn't random. You start with applications that have little risk and few dependencies. That gives your team experience and confidence before you get to the critical systems.
In this phase you also define your target architecture for network and security. VPN connections to the datacenter, firewall rules, identity management, encryption. It's tempting to do this later. That's a mistake. Security issues you bake in during migration are expensive to fix afterwards.
Phase 3: Migration execution
The execution itself is, ironically, often the most straightforward part. At least if discovery and planning were done well. With a lift-and-shift you copy virtual machines or data to the target platform. With a replatform you adjust configurations. With a refactor you rebuild.
What every migration has in common: test thoroughly before you switch off the old environment. Run the new and old environments in parallel. Compare performance. Check that data came over correctly. Let end users test in the new environment before you switch the DNS.
The biggest risks in this phase are data loss and downtime. Both are avoidable with the right preparation. You prevent data loss with verifiable backups and checksums. You minimise downtime by scheduling migrations outside office hours, lowering DNS TTLs beforehand, and having a tested rollback procedure ready.
Phase 4: Optimisation and management
The migration is done. Your applications run in the cloud. Now the real work begins.
The first months after a migration are critical for cost control. Most organisations pay too much initially, because they sized their cloud resources based on their old hardware (which was almost always oversized). Monitor your actual usage and scale back where you can. Most cloud providers offer cost analysis tools. Use them.
Optimisation is also about performance. Latency patterns change when you go from local servers to an external datacenter. Database queries that were fast on-premise can become slower when the distance to the server increases. Monitor, measure, and adjust.
And finally: management. Who monitors your cloud environment? Who patches the operating systems on your virtual machines? Who manages the firewall rules? If you have managed hosting, your provider does that. With IaaS (infrastructure as a service), you do it yourself. Make sure those responsibilities are crystal clear before the migration is done, not after.
Cloud migration: the 4 phases
Based on AWS Well-Architected Framework · Gartner Migration Methodology
The three biggest mistakes
After hundreds of migrations in the market, three mistakes keep recurring.
No exit strategy. Organisations are so focused on the migration to the cloud that they forget to think about the scenario where they want to get out again. Vendor lock-in is a real risk. If your applications become deeply intertwined with provider-specific services, a future migration to another provider becomes exponentially more expensive. That shouldn't stop you, but it should be a conscious choice.
Security as an afterthought. "We'll do that when everything is running." No. Security architecture is determined upfront. Identity management, network segmentation, encryption, logging. It's cheaper to do it right during the migration than to fix it afterwards. And with the Cybersecurity Act coming, it's no longer an optional extra.
Forgetting the organisation. A cloud migration isn't just a technical project. Work processes change. Responsibilities shift. Your IT team needs to learn new skills. Users need to get used to a different environment. The organisations that migrate most successfully invest as much in change management as in technology.
The bottom line
Cloud migration isn't a technical trick. It's a strategic operation that affects your infrastructure, your security, your costs, and your organisation. The technology is the easy part. The hard part is in the choices you make before the first server is moved.
Start with an honest inventory of what you have. Choose the right migration strategy per application. Plan the sequence, the security, and the rollback. Execute with parallel environments and thorough testing. And optimise afterwards, because the cloud isn't a destination but an ongoing management model.
The organisations that do this well end up with infrastructure that's more flexible, more secure, and easier to manage than what they had. The organisations that skip it end up with the same problems, but in the cloud.