Cloud Migration Handbook

cloud
migration
infrastructure
A step-by-step guide to migrating your applications and infrastructure to the cloud
Published

February 15, 2025

Cloud Migration Handbook

Introduction

This handbook provides a comprehensive approach to migrating applications and infrastructure to the cloud. It covers the entire migration journey from initial assessment through planning, execution, and optimization.

Migration Strategy

Migration Approaches

There are several approaches to cloud migration, often referred to as the “6 Rs”:

  1. Rehost (Lift and Shift): Move applications without modification
  2. Replatform (Lift and Reshape): Make minor modifications to take advantage of cloud capabilities
  3. Refactor/Re-architect: Significantly modify applications to optimize for cloud
  4. Repurchase (Drop and Shop): Replace with cloud-native alternatives
  5. Retire: Decommission unnecessary applications
  6. Retain: Keep certain applications on-premises

Each approach has different benefits, challenges, and resource requirements. The right approach depends on application characteristics, business requirements, and organizational constraints.

Migration Strategy Development

Develop a migration strategy that includes:

  • Business case and objectives: Define the expected benefits and success criteria
  • Application portfolio assessment: Analyze applications for migration suitability
  • Migration approach selection: Choose the appropriate approach for each application
  • Technical strategy: Define the target architecture and platform selection
  • Resource planning: Identify the skills and resources needed
  • Timeline and roadmap: Establish a realistic timeline for migration

Assessment Phase

Business Assessment

Evaluate business factors affecting migration:

  • Strategic objectives: Alignment with business strategy
  • Financial considerations: Cost models and ROI analysis
  • Regulatory and compliance requirements: Legal constraints and compliance needs
  • Operational impact: Effect on business processes
  • Stakeholder needs: Expectations and concerns of various stakeholders

Application Assessment

Analyze applications for cloud readiness:

  • Application inventory: Catalog all applications and their components
  • Dependencies: Identify application dependencies and integration points
  • Usage patterns: Understand usage patterns and performance requirements
  • Data characteristics: Analyze data volume, sensitivity, and compliance requirements
  • Technical compatibility: Evaluate compatibility with cloud platforms
  • Migration complexity: Assess the complexity of migration

Infrastructure Assessment

Evaluate current infrastructure:

  • Server inventory: Document server specifications and utilization
  • Network architecture: Analyze network design and connectivity
  • Storage systems: Catalog storage requirements and data volumes
  • Security controls: Document existing security measures
  • Monitoring and management: Assess current operational tools
  • Disaster recovery: Evaluate existing DR capabilities

Planning Phase

Target Architecture Design

Design the cloud environment:

  • Cloud service model: Choose appropriate service models (IaaS, PaaS, SaaS)
  • Cloud deployment model: Select deployment model (public, private, hybrid, multi-cloud)
  • Cloud provider selection: Evaluate and select cloud providers
  • Architecture patterns: Define architecture patterns for different application types
  • Security architecture: Design security controls and compliance measures
  • Networking: Design cloud networking and connectivity solutions
  • Identity and access management: Plan for identity integration and access controls

Migration Planning

Develop detailed migration plans:

  • Application prioritization: Sequence applications for migration
  • Migration waves: Group applications into logical migration waves
  • Detailed migration runbooks: Create step-by-step migration procedures
  • Testing strategy: Define testing approach for each application
  • Rollback procedures: Establish rollback plans in case of migration issues
  • Cutover planning: Plan for the transition from on-premises to cloud

Operational Planning

Prepare for cloud operations:

  • Cloud governance: Establish governance framework for cloud resources
  • Operational procedures: Develop cloud operations procedures
  • Monitoring and management: Set up monitoring and management tools
  • Support model: Define support model for cloud services
  • Disaster recovery: Design cloud-based disaster recovery capabilities
  • Cost management: Implement cost monitoring and optimization processes

Execution Phase

Foundation Implementation

Establish the cloud foundation:

  • Cloud accounts and subscriptions: Set up cloud accounts and billing
  • Identity and access management: Implement identity services and access controls
  • Network infrastructure: Configure virtual networks and connectivity
  • Security controls: Implement security services and controls
  • Monitoring and logging: Set up monitoring and logging infrastructure
  • Service management: Configure service management tools

Migration Execution

Execute the migration:

  • Data migration: Transfer data to cloud storage
  • Application migration: Migrate applications according to selected approach
  • Testing and validation: Verify functionality and performance
  • Cutover execution: Transition from on-premises to cloud services
  • Post-migration validation: Confirm successful migration
  • Decommissioning: Retire on-premises resources when appropriate

Operational Transition

Transition to cloud operations:

  • Operational handover: Transfer responsibility to operations teams
  • Knowledge transfer: Train operations staff on cloud services
  • Documentation updates: Update operational documentation
  • Support transition: Establish cloud support processes
  • Performance monitoring: Monitor application performance in cloud
  • Incident management: Refine incident response for cloud environment

Optimization Phase

Performance Optimization

Improve cloud performance:

  • Performance analysis: Analyze application performance in cloud
  • Scaling optimization: Adjust scaling parameters for optimal performance
  • Resource sizing: Right-size cloud resources based on actual usage
  • Service tuning: Tune cloud services for better performance
  • Architecture improvements: Implement architectural improvements

Cost Optimization

Manage and optimize costs:

  • Cost analysis: Analyze cloud spending patterns
  • Resource optimization: Eliminate unused or underutilized resources
  • Reserved capacity: Utilize reserved instances for stable workloads
  • Pricing model optimization: Select optimal pricing models
  • Automated cost controls: Implement automated cost management
  • Continuous improvement: Establish ongoing cost optimization processes

Operational Optimization

Refine cloud operations:

  • Process automation: Automate operational tasks
  • Self-service enablement: Implement self-service capabilities
  • Continuous improvement: Refine operational procedures
  • Skill development: Build cloud expertise in operations teams
  • Service level optimization: Refine service level agreements
  • Operational analytics: Use operational data to drive improvements

Cloud Migration Patterns

Rehost (Lift and Shift) Pattern

Implementation approach:

  1. Discover: Identify servers and dependencies
  2. Plan: Create migration plan with minimal changes
  3. Replicate: Clone servers to cloud environment
  4. Test: Verify functionality in cloud
  5. Cutover: Switch traffic to cloud instances
  6. Optimize: Make post-migration adjustments

Best suited for: - Legacy applications with few dependencies - Applications with stable workloads - Time-sensitive migrations - Applications planned for later modernization

Replatform (Lift and Reshape) Pattern

Implementation approach:

  1. Assess: Identify opportunities for platform changes
  2. Design: Design target platform changes
  3. Modify: Make necessary application changes
  4. Migrate: Move to cloud with platform changes
  5. Test: Verify functionality with new platform
  6. Optimize: Tune for the new platform

Best suited for: - Applications with clear platform upgrade paths - Database applications that can benefit from managed databases - Applications with scaling issues in current platform - Applications requiring improved resilience

Refactor/Re-architect Pattern

Implementation approach:

  1. Analyze: Perform detailed application analysis
  2. Design: Create cloud-optimized architecture
  3. Refactor: Modify application for cloud-native capabilities
  4. Implement: Build cloud-native infrastructure
  5. Migrate: Deploy refactored application to cloud
  6. Optimize: Fine-tune cloud-native implementation

Best suited for: - Strategic applications with long lifecycles - Applications requiring significant scalability or performance improvements - Applications with substantial technical debt - Applications that need to leverage cloud-native services

Migration Challenges and Solutions

Common Challenges

Address these frequent migration challenges:

  1. Dependency complexity: Applications with many dependencies
    • Solution: Detailed dependency mapping and migration group planning
  2. Data migration: Large data volumes or strict consistency requirements
    • Solution: Staged data migration approach and appropriate tools
  3. Cutover windows: Minimizing downtime during transition
    • Solution: Effective cutover planning and rehearsals
  4. Application compatibility: Issues with cloud compatibility
    • Solution: Pre-migration testing and remediation
  5. Network performance: Latency and bandwidth challenges
    • Solution: Network optimization and CDN implementation
  6. Security and compliance: Meeting security requirements in cloud
    • Solution: Security controls mapping and cloud-native security services

Risk Mitigation

Implement these risk mitigation measures:

  • Phased approach: Start with lower-risk applications
  • Pilot migrations: Test process with representative applications
  • Rollback capabilities: Ensure ability to return to on-premises
  • Pre-migration testing: Thoroughly test before production migration
  • Incremental approach: Use incremental steps when possible
  • Contingency planning: Prepare for potential issues

Multi-Cloud Considerations

Multi-Cloud Strategy

Develop an effective multi-cloud approach:

  • Cloud selection criteria: Define criteria for choosing clouds for workloads
  • Workload placement: Determine optimal placement for each workload
  • Consistency: Establish consistent processes across clouds
  • Integration: Design integration between cloud platforms
  • Governance: Implement unified governance across clouds
  • Operational model: Define operations for multi-cloud environment

Multi-Cloud Challenges

Address common multi-cloud challenges:

  • Skills diversity: Need for expertise across platforms
  • Management complexity: Increased operational overhead
  • Cost visibility: Complex cost management across providers
  • Security consistency: Maintaining consistent security controls
  • Operational consistency: Standardizing operations across platforms
  • Cross-cloud dependencies: Managing services that span clouds

Team and Organization

Migration Team Structure

Establish an effective migration team:

  • Migration program office: Provide overall governance
  • Cloud platform team: Design and implement cloud foundation
  • Migration factory team: Execute migrations at scale
  • Application teams: Support application-specific migration tasks
  • Operations team: Prepare for operational transition
  • Security team: Ensure security compliance throughout migration

Skills and Training

Develop necessary cloud skills:

  • Skill assessment: Identify current skills and gaps
  • Training plan: Develop training for different roles
  • Certification paths: Establish cloud certification targets
  • Hands-on experience: Provide practical experience opportunities
  • External expertise: Leverage partners when needed
  • Knowledge sharing: Create mechanisms to share learnings

Conclusion

Cloud migration is a transformative journey that requires careful planning, execution, and optimization. By following a structured approach and leveraging established patterns, organizations can successfully migrate to the cloud while minimizing risks and maximizing benefits.

Remember that migration is not just a technical exercise—it requires alignment with business objectives, effective change management, and organizational adaptation. The cloud journey continues after migration with ongoing optimization to fully realize the benefits of cloud computing.

References and Resources

  • AWS Cloud Adoption Framework
  • Microsoft Cloud Adoption Framework
  • Google Cloud Adoption Framework
  • Cloud Security Alliance Cloud Controls Matrix
  • NIST Cloud Computing Standards