Cloud Migration: A Practical Guide to Moving to AWS, Azure, or GCP

Cloud migration is one of the most strategically important decisions a growing business will make. Done well, it reduces infrastructure costs by 30–50%, eliminates the operational burden of managing physical servers, enables global scale, and significantly improves business continuity. Done badly, it creates months of disruption, unexpected bills, performance problems, and security vulnerabilities that did not exist before.

This guide covers what cloud migration actually involves, how to choose the right cloud provider for your business, what it costs, and how to avoid the mistakes that turn migrations into expensive projects.

What Cloud Migration Actually Means

"Moving to the cloud" covers a spectrum of activities. At one end: simply moving virtual machine images from your on-premise servers to cloud-hosted virtual machines — changing very little except where the servers sit. At the other end: fully re-architecting applications to use managed cloud services, eliminating servers entirely in favour of serverless functions, managed databases, and auto-scaling infrastructure.

The right migration approach depends on your timeline, budget, risk tolerance, and technical debt. The industry uses a "6 Rs" framework:

Rehost (Lift and Shift) Move your servers to the cloud with minimal changes. Fastest and lowest risk. Does not deliver all the benefits of cloud-native architecture but is often the right starting point for time-constrained migrations.

Replatform (Lift, Tinker, and Shift) Make targeted optimisations during migration — for example, moving from a self-managed database to a managed database service. Captures meaningful cost and operational savings without a full rebuild.

Refactor / Re-architect Rebuild applications to use cloud-native services: managed queues, serverless functions, auto-scaling groups, content delivery networks. Highest effort and longest timeline, but delivers the full cost, performance, and resilience benefits of modern cloud architecture.

Retire Identify systems that are no longer needed and decommission them during the migration. Most migrations find that 10–20% of systems can simply be turned off.

Retain Keep some systems on-premise, at least for now. Not everything makes sense to migrate immediately — particularly legacy systems with complex dependencies or hardware-specific requirements.

Replace Swap out legacy applications for cloud-based SaaS alternatives. For example, replacing a self-hosted email server with Google Workspace, or replacing a custom CRM with Salesforce.

A real migration plan uses all six strategies across different systems — not a single blanket approach.

Which Cloud Provider is Right for Your Business?

Amazon Web Services (AWS) The market leader globally, with regions on every inhabited continent, so you can usually host close to your users. AWS has the broadest service catalogue and the largest talent pool of certified engineers worldwide.

Microsoft Azure The second choice for most enterprise organisations, particularly those already heavily invested in Microsoft products (Office 365, Active Directory, SQL Server). Azure has a large global region footprint and strong enterprise support and hybrid connectivity options for businesses with on-premise Microsoft infrastructure. Azure is often the choice for regulated industries due to enterprise compliance certifications.

Google Cloud Platform (GCP) Google has the best global network infrastructure and the strongest managed Kubernetes offering (GKE). GCP pricing is frequently more competitive than AWS for compute and egress. GCP is a strong choice for businesses with large data processing or analytics workloads.

For most SMEs and mid-market businesses: start with AWS in the region closest to your users. The service breadth and talent availability make it the pragmatic choice. Enterprise businesses already in the Microsoft ecosystem should evaluate Azure seriously.

What Does Cloud Migration Cost?

Cloud migration costs fall into three categories:

Migration project costs (one-time) This is what you pay the engineering team to plan and execute the migration. Range: USD 10,000 – USD 150,000+ depending on the size and complexity of your environment.

Simple migrations (single application, straightforward infrastructure): USD 10,000 – USD 30,000 Mid-size migrations (5–20 applications, database migrations, some refactoring): USD 30,000 – USD 100,000 Complex migrations (enterprise environment, multiple integrations, regulatory requirements): USD 100,000+

Ongoing cloud infrastructure costs (recurring) What you pay the cloud provider monthly. For a typical SME running 3–5 production applications: USD 800 – USD 3,000/month on AWS. For larger enterprises: USD 5,000 – USD 30,000+/month. These costs replace (and typically reduce) what you were spending on hardware, data centre space, power, and IT operations.

Optimisation and training (one-time to ongoing) Cloud cost optimisation — reserved instances, rightsizing, spot instance strategies — can reduce bills by 30–50% but requires skilled engineering effort. Budgeting USD 5,000 – USD 15,000 for a post-migration optimisation engagement is typical.

The Five Most Common Migration Mistakes

1. Migrating without a dependency map Before moving any system, you need a complete picture of how every application talks to every other application. Undocumented dependencies — a marketing system silently calling the ERP API, a scheduled job pulling from a server that is being decommissioned — are the most common cause of post-migration failures. Invest time in mapping dependencies before touching anything.

2. Moving everything at once Large-bang migrations are high risk. The correct approach is to migrate in waves: non-critical systems first, core business systems last. This builds team confidence, surfaces unexpected issues on low-stakes systems, and keeps the business running normally throughout.

3. Ignoring data egress costs Cloud providers charge very little to move data in, but charge meaningfully for data leaving their networks (egress). Applications that export large volumes of data — reporting systems, backup tools, video platforms — can generate unexpected monthly bills if egress is not modelled during planning.

4. Lifting and shifting a system that needed to be rebuilt Cloud migration is sometimes used as an opportunity to defer necessary refactoring. Running a slow, poorly-architected application on cloud VMs will not make it faster or more reliable — it will just cost more per month than the on-premise server did. Identify systems that need re-architecture and plan for it rather than assuming "the cloud will fix it."

5. Under-investing in security reconfiguration Cloud security operates on a shared responsibility model: the provider secures the infrastructure, you secure everything you put on it. Misconfigured S3 buckets, overly permissive IAM roles, security groups that allow broad internet access, and unencrypted storage are among the most common sources of data breaches. A security review of your cloud configuration should be part of every migration, not an afterthought.

How Long Does a Cloud Migration Take?

Realistic timelines:

• Single web application, rehost: 2–4 weeks
• SME environment (3–10 applications, databases): 2–4 months
• Mid-market organisation (20+ applications, integrations, data migrations): 4–9 months
• Enterprise migration (complex legacy systems, regulatory requirements): 9–18 months

These timelines assume adequate resourcing and executive sponsorship. Migrations that are under-resourced or paused for budget approval cycles typically take 2–3× longer and cost significantly more than the original estimate.

How We Approach Cloud Migrations

We have migrated production environments for businesses across Europe, Africa, and North America. Our approach:

Discovery phase (1–2 weeks): We map your current infrastructure, applications, dependencies, and data flows. We build a complete picture of what exists before proposing what to move and how.

Migration strategy (1 week): We apply the 6 Rs framework to every system and build a prioritised migration plan with wave structure, risk assessment, and timeline.

Execution (varies by scope): We conduct migrations with zero-downtime processes where possible — blue/green deployments, database replication, DNS cutover. We do not schedule weekend maintenance windows that put your business at risk.

Security hardening: Every environment we migrate receives a security configuration review as standard: IAM policy audit, network security group review, encryption configuration, secrets management.

Handover: You receive full infrastructure-as-code (Terraform), documented architecture, runbooks, and a knowledge transfer session. You are never dependent on us to understand your own infrastructure.

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