The 6 Rs of Cloud Migration Strategy: Framework, Use Cases, and Deployment Models

Modern organizations no longer view cloud adoption as optional. The question is not whether to migrate, but how to execute cloud transformation without compromising performance, security, or continuity. Enterprises today manage a complex mix of legacy systems, hybrid infrastructure, and rapidly evolving business applications. To ensure technical and operational alignment, organizations must classify each workload and migration opportunity with precision.

That’s where the 6 Rs of cloud migration come into play. Originally developed by Amazon Web Services (AWS), the 6 Rs model provides a strategic framework for evaluating, planning, and implementing application-level migration decisions. The six migration strategies—Rehost, Replatform, Repurchase, Refactor, Retire, and Retain—offer clear paths for managing diverse infrastructure elements across cloud, on-prem, or hybrid environments.

This guide explains each of the 6 Rs in detail, with practical examples, risk assessments, and business fit analysis. It also helps decision-makers understand how to apply the model to real-world use cases and how CitySource Solutions supports cloud migration at every phase—from infrastructure discovery to post-migration optimization.

What Are the 6 Rs of Cloud Migration?

Cloud migration involves more than just moving data from on-premise servers to cloud infrastructure. It requires strategic planning and technical execution aligned with business goals, regulatory frameworks, and system dependencies. The 6 Rs of cloud migration provide a proven framework to classify and execute migration strategies at the application level.

Origin of the AWS 6 Rs Model

The 6 Rs model was first introduced by Amazon Web Services (AWS) as part of its Cloud Adoption Framework (CAF). It simplifies complex migration decisions by assigning one of six paths to each application or system component based on its architecture, criticality, and cloud-readiness. Over time, Microsoft Azure and Google Cloud have adopted similar variants, reinforcing the model’s cross-platform applicability.

The purpose of the model is to:

  • Simplify cloud transformation planning
  • Minimize business disruption
  • Maximize long-term infrastructure value
  • Classify workloads with tactical precision

Each “R” represents a specific migration strategy and comes with distinct operational impact, cost implication, and modernization potential.

The 6 Rs of Cloud Migration Framework (Table)

StrategyDefinitionBest ForRisk LevelEffort Level
RehostLift-and-shift without code changesLegacy applications with minimal flexibilityLowLow
ReplatformMinor changes to optimize for cloudApps requiring OS or DB upgradesMediumLow–Medium
RepurchaseReplace with SaaS alternativeCommercial apps with high license costsMediumMedium
RefactorRedesign application architectureMission-critical systems needing scalabilityHighHigh
RetireDecommission unused appsRedundant or outdated softwareNoneMedium
RetainKeep on-prem as-is temporarilySystems not cloud-compatible or still valuableLowNone

Quick Definitions of the 6 Rs

Rehost: Also known as “lift-and-shift,” rehosting involves moving applications as-is to the cloud with no code changes. This is the fastest path but offers limited cloud-native benefits.

Replatform: This approach modifies underlying components such as databases or operating systems to better suit the cloud, without rewriting the core application.

Repurchase: Often applied to commercial off-the-shelf (COTS) software, repurchasing replaces existing tools with Software-as-a-Service (SaaS) solutions.

Refactor: Refactoring involves rewriting applications using cloud-native services, such as microservices, containers, and serverless architecture. This offers long-term performance and scalability gains.

Retire: Applications that are obsolete or unused can be decommissioned entirely, freeing up budget and reducing security risk.

Retain: In cases where applications are bound by regulatory or latency constraints, the best option may be to retain them on-premise for the time being.

How to Choose the Right 6 R Path for Your Business

Selecting the correct migration strategy from the 6 Rs framework requires a detailed evaluation of your application portfolio, infrastructure dependencies, compliance mandates, and long-term technology goals. No single strategy fits all workloads. Successful migrations depend on mapping each application or system to the most appropriate “R” based on technical feasibility and business value.

Migration planning should begin with a cloud readiness assessment. This includes discovering and cataloging existing systems, scoring applications by criticality, identifying integration points, and classifying infrastructure elements by performance, storage, and access requirements.

Key Evaluation Criteria

Before assigning an R strategy to any application, assess the following:

  • Application Criticality:
    Determine if the application supports core operations, internal workflows, customer interactions, or compliance. Mission-critical applications may require refactor or replatform strategies for future-proofing.
  • Integration Dependencies:
    Legacy apps often connect to other services or databases. These dependencies must be mapped and validated to avoid downstream failures during rehosting or replatforming.
  • Technical Debt:
    Evaluate code age, documentation, and customization. High-entropy or undocumented apps are poor candidates for refactoring and may be better suited for rehost or retire paths.
  • Security & Compliance:
    Applications handling financial data, patient records, or regulated IP may need retention, on-premise protection, or hardened cloud configurations to satisfy frameworks such as HIPAA, PCI-DSS, or SOX.
  • Business Continuity Requirements:
    If an application cannot tolerate downtime during transition, options like blue-green deployments or phased migrations become essential, impacting the choice between refactor and rehost.
  • Cost Model Alignment:
    Migration effort should reflect future ROI. Applications nearing end-of-life may not justify refactoring. In contrast, high-cost licensing software may be prime for repurchase via SaaS alternatives.

Industry-Specific Examples

IndustryUse CaseRecommended Strategy
HealthcarePatient records platform with HIPAA complianceRetain or Refactor
FinanceOn-prem investment analytics suite (COTS)Repurchase or Rehost
RetailInventory management system requiring web scalingReplatform or Refactor
LegalInternal document archives with audit trailsRehost
ManufacturingOutdated ERP system with unused modulesRetire and Repurchase

CitySource Solutions uses this same assessment framework to guide clients through application scoring workshops, dependency mapping, and migration planning. Each system is evaluated not just on cloud compatibility, but on its total value within the organization’s technology and business stack.

Rehost vs Refactor: Which Delivers ROI Faster?

Among the six cloud migration strategies, Rehost and Refactor are the most commonly debated options, especially for businesses evaluating cost-efficiency versus future scalability. Each approach serves a different technical purpose and impacts ROI, operational disruption, and long-term maintainability in distinct ways. The choice must align with infrastructure maturity, internal capabilities, and business timelines.

When Rehost Offers Faster ROI

Rehosting—commonly known as “lift-and-shift”—involves migrating applications to cloud environments without modifying the underlying code or architecture. For many legacy systems and packaged software, this strategy provides a rapid, low-risk path to cloud adoption.

Rehosting delivers faster ROI in these scenarios:

  • Short timelines or executive pressure to “get to cloud”
  • Limited internal DevOps or cloud engineering capability
  • Tightly coupled legacy applications with fragile dependencies
  • Temporary cloud deployments pending future modernization

The primary benefit is reduced capital expense on hardware and real estate while maintaining business continuity. However, rehosting fails to leverage most cloud-native features like auto-scaling, fault tolerance, or advanced orchestration.

Businesses using our business-optimized cloud computing services often start with rehosting to minimize migration friction. We then build phased roadmaps toward replatforming or refactoring based on system usage and performance metrics.

When Refactor Maximizes Long-Term Value

Refactoring involves rewriting or re-architecting applications to fully exploit cloud-native services such as microservices, serverless compute, container orchestration, and distributed databases. While the upfront investment is significantly higher, the long-term returns in performance, flexibility, and security are substantial.

Refactor is ideal when:

  • Applications require scalability under unpredictable load
  • The existing architecture is monolithic, outdated, or brittle
  • Your team is adopting CI/CD pipelines and DevOps workflows
  • Business drivers demand real-time analytics, elasticity, or API-first design

For example, an eCommerce platform that experiences seasonal traffic spikes and demands instant checkout updates benefits immensely from a refactored microservices model hosted on AWS Fargate or Azure Functions.

CitySource often incorporates refactoring as part of an end-to-end cloud migration strategy, allowing clients to modernize high-priority workloads while maintaining hybrid infrastructure during transition.

Which Strategy Is Right for You?

If the objective is speed and cost-reduction, rehost provides immediate infrastructure offloading. But if agility, performance, and long-term automation are priorities, refactoring becomes the superior investment.

In practice, most organizations adopt a hybrid migration path—rehosting non-critical systems while refactoring mission-critical applications over time. This ensures operational stability while unlocking the full economic potential of cloud transformation.

Common Mistakes in Applying the 6 Rs Framework

While the 6 Rs framework simplifies cloud migration planning, incorrect implementation often leads to stalled projects, budget overruns, or misaligned infrastructure. Many organizations assume assigning an “R” to an application is a one-time decision, but in practice, effective migration requires ongoing evaluation, cross-functional coordination, and platform-level visibility.

Mistake 1: Treating All Applications the Same

A frequent error is applying a uniform migration strategy—typically rehosting or replatforming—to all systems without context. Legacy workloads, mission-critical applications, or highly customized software require differentiated approaches.

For example, companies often attempt to rehost ERP platforms and CRM systems without evaluating cloud compatibility. This results in performance bottlenecks or compliance failures. At CitySource Solutions, we use structured discovery and scoring methods within our end-to-end cloud migration support to ensure each application is aligned with its optimal R path based on cost, complexity, and interdependencies.

Mistake 2: Ignoring Hidden Dependencies

Many legacy applications interact with file shares, proprietary protocols, or internal databases that are poorly documented or hard-coded. Rehosting or repurchasing such systems without full dependency mapping leads to broken integrations, failed automation scripts, or delayed service delivery.

Businesses should utilize application dependency mapping tools and involve infrastructure teams early in the migration process. This ensures that even background services, scheduled tasks, and authentication layers are migrated or modernized together.

Mistake 3: No Sunset Strategy for Retired Systems

The Retire strategy is often underused because organizations lack formal processes to decommission applications. Without structured asset retirement, unused systems continue consuming cloud resources or expose security risks through unmonitored endpoints.

Retirement planning must include:

  • Data export or archival plans
  • Documentation of replacement tools
  • Internal stakeholder sign-off
  • Network-level service isolation

Mistake 4: Selecting Rs Without Outcome Metrics

Many migrations proceed without defining success metrics per application. Whether the strategy is Rehost or Refactor, measurable goals—such as load time improvement, uptime percentages, or license savings—must be established during planning.

At CitySource, we pair each R strategy with outcome tracking via SLAs, resource utilization dashboards, and managed IT support services to maintain post-migration optimization and business continuity.

Avoiding These Errors with Expert Guidance

Proper application classification is a process, not a checkbox. Our team at CitySource applies proven frameworks to prevent missteps at every phase—from risk identification to post-launch validation—ensuring every system transition aligns with operational and strategic priorities.

How We Use the 6 Rs in Real Migration Projects

At CitySource Solutions, the 6 Rs framework is not a theoretical exercise—it is the backbone of our real-world cloud migration methodology. Every engagement begins with structured analysis, not assumptions. Our approach transforms abstract R classifications into actionable roadmaps supported by engineering precision, operational control, and long-term accountability.

Discovery-Driven Planning Process

We start each migration with a comprehensive discovery workshop, involving IT stakeholders, compliance officers, and department leads. The objective is to classify every application and system component according to its business function, technical dependencies, and migration complexity.

Our 3-step classification method includes:

  1. Application Inventory and Tagging
    We create an asset register that includes infrastructure components, business systems, licenses, usage logs, and security profiles.
  2. R Strategy Assignment by Workload
    Each asset is scored for readiness, cost-to-migrate, and post-migration value. Systems are then assigned a preliminary R path—Rehost, Replatform, etc.—with an explanation of why that strategy delivers the best balance of performance, cost, and uptime.
  3. Stakeholder Validation
    Migration decisions are finalized only after mapping all dependencies and securing approvals from key business units. This ensures the final migration strategy reflects technical feasibility and organizational buy-in.

Technology Stack & Cloud Tools We Use

We don’t guess—our migration decisions are backed by leading assessment and orchestration tools, including:

  • AWS Migration Hub and Application Discovery Service
    For agent-based and agentless scanning of workloads, usage, and configuration patterns
  • Azure Migrate and Dependency Visualization
    For Windows Server, SQL workloads, and hybrid Azure Stack transitions
  • CloudEndure & DMS (Database Migration Service)
    For low-downtime lift-and-shift and cross-region replication
  • Infrastructure-as-Code (IaC)
    Using tools like Terraform and CloudFormation to enable repeatable, automated cloud environment deployment

By combining tooling with our team’s infrastructure experience, we reduce risk and deliver transparent, auditable outcomes. Many clients complement this process with business-optimized cloud computing to ensure their environment runs at peak efficiency after migration.

Post-Migration Optimization

Our work doesn’t stop at go-live. We monitor systems using proactive metrics dashboards, enforce patching schedules, and support environments through our managed support and helpdesk services. This ensures the selected R strategy continues to deliver value long after deployment.

FAQs About the 6 Rs of Cloud Migration

Below are the most frequent questions business leaders, IT managers, and compliance officers ask during 6 Rs assessments. Each response reflects current cloud architecture standards, platform-neutral strategy, and lessons from hundreds of successful deployments.

What is the most commonly used migration strategy?

Rehost is the most widely applied strategy, particularly for first-time migrations or when legacy applications must be moved quickly. It offers a short deployment timeline and low technical complexity, but it does not fully utilize cloud-native benefits. Over time, rehosted systems are often refactored or replaced.

Can a single application use more than one R strategy?

Yes. Complex applications may require hybrid strategies. For instance, a monolithic ERP system might be refactored for its customer-facing components, rehosted for reporting modules, and retired for unused legacy add-ons. CitySource classifies systems at the component level, not just by application title, for precise planning.

How long does a typical migration take per R path?

StrategyTypical Timeframe (per system)
Rehost2–4 weeks
Replatform3–6 weeks
Repurchase1–2 weeks post-licensing
Refactor8–16 weeks
Retire1–3 weeks
RetainImmediate (no migration)

Timeframes depend on system complexity, data volume, testing cycles, and approval checkpoints. Our end-to-end cloud migration support includes project management that aligns technical steps with operational milestones.

Which Rs are most suitable for legacy Windows servers?

Most legacy Windows workloads are candidates for Rehost, Replatform, or Retire, depending on their function. We assess these systems for Active Directory dependencies, Windows licensing, SQL Server supportability, and Group Policy use before determining the optimal path. In regulated sectors, Retain may apply temporarily for compliance holdovers.

What tools help assess and assign the 6 Rs?

We use a range of platform-native and third-party tools:

  • AWS Migration Evaluator for resource and cost modeling
  • Azure Migrate for compatibility and dependency analysis
  • Dynatrace or AppDynamics for application behavior tracking
  • Terraform/CloudFormation for repeatable deployments

These tools integrate directly with our cloud computing services, reducing human error and expediting decision timelines.

Ready to Apply the Right R Strategy?

Cloud migration is not just a move—it’s a transformation. Selecting the right R strategy ensures your systems are optimized not just for today’s workloads, but for tomorrow’s scale, compliance, and resilience.

CitySource Solutions guides businesses through every phase of the migration lifecycle, combining strategic insight with technical depth. From early discovery to ongoing managed IT support, we ensure each R decision contributes to long-term success.

📞 Contact us today to start your migration with clarity, speed, and confidence.