Cloud migration is one of the most impactful - and most misunderstood - initiatives an organization can undertake. After leading migrations across AWS, Azure, and GCP for over a dozen client engagements, I've distilled my approach into a repeatable five-step framework that balances speed with safety.
Step 1: Discovery & Assessment
Every successful migration starts with understanding what you actually have. I begin with a comprehensive inventory of existing infrastructure: servers, databases, networking topology, dependencies, and traffic patterns. Tools like AWS Application Discovery Service and Azure Migrate can automate much of this, but nothing replaces conversations with the teams who built and operate the systems.
Key deliverables from this phase include a dependency map, a workload classification (by criticality and complexity), and a preliminary TCO comparison between current on-prem costs and projected cloud spend. I've found that organizations consistently underestimate their true on-prem costs by 30-40% when they forget to account for facilities, power, cooling, and staff overhead.
Step 2: Strategy Selection (The 6 R's)
Not every workload should be migrated the same way. I use the 6 R's framework to categorize each application:
- Rehost (lift-and-shift) - move as-is for quick wins
- Replatform - minor optimizations during migration (e.g., swap to RDS instead of self-managed MySQL)
- Repurchase - replace with a SaaS solution
- Refactor - re-architect for cloud-native (microservices, serverless)
- Retire - decommission applications nobody uses
- Retain - keep on-prem for now (compliance, latency requirements)
In practice, I've found that 60-70% of workloads in a typical enterprise can be rehosted or replatformed, delivering fast ROI while you plan deeper refactoring for the remaining high-value applications.
Step 3: Landing Zone & Foundation
Before migrating a single workload, you need a solid foundation. This means building your landing zone: a well-architected multi-account structure with networking, security baselines, IAM policies, and logging already in place.
I use Terraform modules to codify the landing zone so it's repeatable across environments and clients. A typical setup includes:
- Organizational Units (OUs) for workload, security, and shared services accounts
- Hub-and-spoke VPC architecture with Transit Gateway
- Centralized logging (CloudTrail, Config, GuardDuty) flowing to a security account
- Baseline IAM roles with least-privilege policies
- DNS and certificate management via Route 53 and ACM
Step 4: Migration Execution
I migrate in waves, starting with low-risk, low-dependency workloads. Each wave follows the same pattern: provision infrastructure with Terraform, deploy the application, run parallel testing, perform the cutover during a maintenance window, then validate with synthetic monitoring.
The most common pitfall I see is skipping the parallel-run phase. Running both environments simultaneously for 1-2 weeks catches data synchronization issues, latency differences, and integration bugs before they become production incidents. Yes, it costs more short-term, but it saves you from the 3 AM "everything is on fire" phone call.
Step 5: Optimization & Operations
Migration doesn't end at cutover. The first 90 days post-migration are critical for right-sizing instances, implementing Reserved Instances or Savings Plans, setting up auto-scaling policies, and tuning monitoring and alerting.
I've consistently achieved 20-35% additional cost savings in this phase by right-sizing over-provisioned instances and switching to graviton-based or spot instances where appropriate. I also establish a FinOps practice with monthly cost reviews, anomaly alerts, and tagging enforcement to prevent cloud spend from creeping back up.
The Bottom Line
Cloud migration is a journey, not a project. The organizations that succeed treat it as a continuous improvement cycle - migrating, optimizing, and iterating. This framework has helped me deliver migrations that reduce costs by 25-35%, improve uptime to 99.95%+, and set teams up for long-term cloud success.