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Cloud Migration Strategy: From Planning to Execution

A comprehensive guide to planning and executing successful cloud migrations—from assessment to post-migration optimization.

1. Why Migrate to Cloud?

Organizations migrate to the cloud for various reasons. Understanding your primary drivers helps shape the right migration strategy:

  • Cost Optimization — Eliminate data center costs, pay-per-use pricing, reduce operational overhead.
  • Scalability — Scale resources on demand, handle traffic spikes, expand globally.
  • Agility — Faster provisioning, experiment quickly, reduce time-to-market.
  • Modernization — Access managed services, adopt DevOps, enable innovation.

2. The 6 R's of Migration

AWS defines six common migration strategies, known as the 6 R's:

Rehost (Lift and Shift)

Move applications as-is to the cloud with minimal changes. Fast but doesn't optimize for cloud-native benefits.

Best for: Quick migrations, applications with limited cloud optimization potential.

Replatform (Lift and Reshape)

Make targeted optimizations without changing core architecture—e.g., move to managed databases or containers.

Best for: Applications that can benefit from managed services with moderate effort.

Refactor / Re-architect

Rebuild applications to be cloud-native, often as microservices or serverless.

Best for: Strategic applications that need scale, agility, or new features.

Repurchase

Move to a different product—typically SaaS. E.g., migrate from custom CRM to Salesforce.

Best for: Applications where SaaS alternatives provide better value.

Retain

Keep applications on-premises, often due to compliance, latency, or complexity.

Best for: Applications not suitable for cloud or not ready to migrate.

Retire

Decommission applications that are no longer needed.

Best for: Legacy applications with no business value or that have been replaced.

3. Migration Assessment

Before migrating, conduct a thorough assessment:

Application Discovery

  • Inventory all applications, dependencies, and data flows
  • Document infrastructure requirements (compute, storage, network)
  • Identify data sensitivity and compliance requirements
  • Map application dependencies and integration points

TCO Analysis

  • Calculate current on-premises costs (including hidden costs)
  • Estimate cloud costs for each migration strategy
  • Factor in migration effort and potential productivity gains
  • Consider reserved capacity discounts in long-term projections

4. Migration Planning

  • 1. Prioritize Applications

    Start with lower-risk applications to build experience. Save complex, critical apps for later.

  • 2. Design Landing Zone

    Set up AWS accounts, networking (VPC, Transit Gateway), security baselines, and operational tooling.

  • 3. Define Migration Waves

    Group related applications together. Consider dependencies and business cycles.

  • 4. Plan Cutover Strategy

    Decide on cutover approach: big bang vs. phased. Plan rollback procedures.

5. Execution Strategies

Database Migration

Use AWS DMS for minimal downtime migrations:

  • Full load + CDC (Change Data Capture) for continuous sync
  • Heterogeneous migrations (e.g., Oracle to Aurora PostgreSQL)
  • Schema conversion with AWS SCT

Application Migration

  • AWS Application Migration Service: Agent-based replication for rehost
  • Containers: Package apps in containers for portability
  • Blue-green deployment: Run parallel environments for safe cutover

6. Common Pitfalls

  • Underestimating dependencies: Discovery must be thorough
  • Lift-and-shift everything: Some apps benefit from optimization
  • Ignoring network planning: Latency and bandwidth matter
  • No rollback plan: Always have a way to revert
  • Skipping security review: Security model changes in cloud
  • Big bang approach for large migrations: Wave-based is safer

7. Post-Migration Optimization

Migration is just the beginning. Post-migration activities maximize cloud value:

  • Right-size resources: Based on actual cloud utilization data
  • Implement reserved capacity: Once usage patterns stabilize
  • Modernize gradually: Adopt managed services over time
  • Establish FinOps: Ongoing cost governance
  • Decommission on-premises: Realize full cost savings

Planning a Cloud Migration?

We help organizations plan and execute successful AWS migrations—from assessment through post-migration optimization.

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