Cloud migration is not a single event; it is a structured process that unfolds across multiple phases, each building on the last. Organisations that treat it as a one-time project rather than a managed programme routinely encounter the same set of problems: missed dependencies, security gaps discovered post-go-live, cost overruns in the first billing cycle, and performance regressions that take weeks to diagnose.
The cloud migration process described in this guide reflects how Rapyder’s engineering teams plan and execute migrations for enterprises across BFSI, healthcare, retail, and technology sectors. It is not theoretical — it is the actual sequence of decisions and actions that determines whether a migration delivers its intended business outcomes within scope, budget, and timeline.
See our detailed cloud migration checklist.
What Is the Cloud Migration Process?
The cloud migration process is the complete sequence of steps an organisation follows to move its applications, data, and infrastructure from on-premises data centres; or from another cloud environment — to a target cloud platform such as Amazon Web Services. It encompasses everything from the initial assessment of what exists today through the ongoing optimisation of what runs in the cloud tomorrow.
The process is not linear in practice; security runs in parallel with architecture design, testing overlaps with later migration waves, and optimisation begins before all workloads have moved. But it does follow a clear directional sequence: understand what you have, decide how to move it, build the environment to receive it, move it carefully, validate it thoroughly, and then improve it continuously.
Comprehensive AWS Cloud Migration Guide.
The 5 Phases of Cloud Migration
At the highest level, every cloud migration moves through five phases:
- Assessment and Preparation: Understanding your current environment, compliance requirements, and business goals.
- Planning and Architecture: Designing your target cloud environment and sequencing the migration.
- Migration Execution: Moving workloads in waves, starting with non-critical systems.
- Validation and Testing: Confirming that migrated systems perform as expected and meet security and compliance requirements.
- Optimisation: Rightsizing resources, reducing costs, and evolving your cloud architecture to take advantage of cloud-native capabilities.
Each phase is explored in the 10-step process below.
Step-by-Step: The Cloud Migration Process
Step 1: Conduct a Cloud Readiness Assessment
The readiness assessment is where migration projects succeed or fail. Its purpose is to give your team an honest, complete picture of what exists in your current environment before any planning begins.
A thorough assessment covers four dimensions. Technical readiness: cataloguing every application, database, server, and dependency, and evaluating whether each is cloud-ready in its current state or requires re-architecture. Financial readiness: calculating the current total cost of ownership (TCO) of your on-premise environment and modelling expected AWS costs post-migration using the AWS Pricing Calculator and AWS Migration Evaluator. Security readiness: identifying compliance requirements, existing security gaps, and data classification. Organisational readiness: evaluating whether your team has the skills and capacity to execute the migration, and identifying where external expertise is needed.
The output of this step is a prioritised migration portfolio, every workload ranked by complexity, risk, and business priority.
Step 2: Establish Your Migration Goals
Goals without metrics are intentions. Before planning begins, define specific, measurable outcomes for the migration. Examples include: reduce infrastructure costs by 30% within 12 months of completing migration; improve application availability from 99.5% to 99.99%; reduce time-to-deploy new features from two weeks to two hours; retire the primary data centre by a specific date.
These goals directly influence migration strategy decisions. If cost reduction is the primary driver, aggressive rightsizing and Reserved Instance commitments belong in the plan from the beginning. If speed-to-cloud is paramount, rehosting (lift-and-shift) is the right initial approach with refactoring deferred to a second phase. Aligning the technical team and the business on goals early prevents strategy conflicts later.
Step 3: Select the Right Migration Strategy for Each Workload
The migration strategy is the single most consequential technical decision in the process. AWS defines six strategies, each representing a different trade-off between speed, effort, and the degree of cloud benefit realised:
- Rehost (lift-and-shift): Move the workload as-is to AWS EC2. Fastest, lowest effort, least cloud-native benefit. Right for organisations that need to vacate a data centre quickly or that have large volumes of legacy applications.
- Replatform: Migrate with targeted optimisations, for example, migrating Oracle databases to Amazon RDS. Delivers meaningful cloud benefits with moderate additional effort.
- Refactor/Re-architect: Redesign the application to use cloud-native services; containers, serverless, microservices. Highest effort, highest long-term return. Right for business-critical applications where performance and scalability are strategic priorities.
- Repurchase: Replace legacy software with cloud-native SaaS. Common for CRM, HR, and collaboration tools.
- Retire: Decommission applications that are no longer serving a business need. Reduces migration scope and ongoing costs.
- Retain: Keep certain workloads on-premise — for compliance, latency, or technical reasons, and revisit in a later cycle.
The output of this step is a migration strategy decision for every workload in your portfolio.
Step 4: Design the Target Cloud Architecture
With migration strategies decided, design the AWS environment your workloads will operate in. This is not just infrastructure provisioning; it is the foundational architecture that will govern security, performance, cost, and scalability for years after migration.
The design process typically follows the AWS Well-Architected Framework across five pillars: Operational Excellence, Security, Reliability, Performance Efficiency, and Cost Optimisation. For multi-account organisations, AWS Control Tower provides a pre-configured landing zone that enforces security guardrails and governance policies across all accounts.
Key architecture decisions at this stage include: VPC design and network topology; account structure and AWS Organizations hierarchy; connectivity to on-premise environments (Direct Connect, VPN, or Transit Gateway); compute services (EC2, ECS, EKS, Lambda); database services; storage architecture; and identity and access management design.
Documenting this architecture as infrastructure-as-code (using AWS CloudFormation or Terraform) ensures reproducibility and reduces configuration drift after go-live.
Step 5: Build and Validate the Landing Zone
Before any workload migrates, build and validate the target AWS environment. This means provisioning your VPCs, configuring security groups, deploying IAM policies, enabling logging (AWS CloudTrail, AWS Config), and confirming that network connectivity between AWS and your on-premise environment is functional and performant.
Run a validation exercise against the empty landing zone before the first workload arrives. Confirm that security controls are in place, that monitoring is working, that cost allocation tags are enforcing correctly, and that your team can access and operate the environment as expected. Discovering a misconfigured IAM policy or a missing network route at this stage costs an hour to fix. Discovering it after 50 workloads have migrated costs days.
Step 6: Execute Migration in Waves
Phased, wave-based migration execution is the industry-standard approach for managing risk across large application portfolios. Divide your migration portfolio into waves, groups of applications with shared characteristics or interdependencies, and migrate one wave at a time.
Wave 1 should contain non-critical, standalone applications. These serve two purposes: they validate that your migration process and tooling are working correctly at small scale, and they give your team hands-on experience before the stakes are high. Common Wave 1 candidates include development environments, internal tools, and test systems.
Subsequent waves progress toward more complex, business-critical systems. For each wave, use AWS Application Migration Service (MGN) to automate continuous server replication from on-premise to AWS, then execute a cutover during a scheduled maintenance window. AWS MGN typically reduces cutover windows to under 30 minutes for most server workloads.
AWS Migration Services — Rapyder.
Step 7: Migrate Databases with Minimal Downtime
Database migration carries the most risk of any component in the migration process. AWS Database Migration Service (DMS) supports over 20 source and target database engines, enabling both homogeneous migrations (for example, Oracle to Oracle on RDS) and heterogeneous migrations (Oracle to Aurora PostgreSQL) with continuous replication that minimises downtime.
For large databases, a multi-stage approach works best: first perform a full load of historical data during off-peak hours, then use AWS DMS change data capture (CDC) to continuously replicate ongoing transactions until cutover. At cutover, stop writes to the source database, allow the final CDC flush to complete, switch the application connection string to the target, and validate data integrity through automated checksums before resuming normal operations.
For datasets exceeding terabytes, AWS Snowball Edge provides physical transfer capacity that bypasses internet bandwidth limitations.
Step 8: Validate Performance and Security Post-Migration
Validation is the step that confirms the migration delivered what it promised. For each migrated workload, run a structured validation sequence.
Functional validation: confirm that all application features work correctly in the AWS environment, with no broken integrations or missing dependencies.
Performance validation: compare response times, throughput, and error rates against pre-migration baselines. If performance has degraded, identify the root cause; it is typically a network configuration issue, an undersized instance, or a database connection pool that needs tuning.
Security validation: confirm that IAM policies are enforcing least-privilege access, that all data is encrypted at rest and in transit, and that network security groups are blocking unintended traffic.
Compliance validation: for regulated workloads, run automated compliance checks using AWS Config Rules against your required standards.
Step 9: Execute Final Cutover and Decommission On-Premise
Final cutover is the moment the production workload switches from on-premise to AWS. Prepare for it with the same rigour as a major product release. Define a detailed cutover runbook with every step, every owner, and every rollback trigger documented in advance. Run the cutover during a scheduled low-traffic window. Have your entire migration team available and have the rollback procedure ready to execute within minutes if needed.
Once cutover is validated and the application is confirmed stable on AWS, begin decommissioning on-premise infrastructure in a phased manner. Do not decommission immediately — maintain on-premise systems in a read-only state for a defined retention period (typically 30–90 days) before final shutdown.
Step 10: Optimise Continuously
Post-migration optimisation is where the financial return on cloud investment is realised. In the first 90 days after go-live, focus on three areas.
Rightsizing: use AWS Compute Optimizer to identify over-provisioned EC2, RDS, and Lambda resources. Migrated workloads are almost always initially over-provisioned, rightsizing typically delivers 20–30% cost reduction without any performance impact.
Commitment-based pricing: once workload utilisation patterns are established (typically after 30–60 days of production data), purchase Reserved Instances or AWS Savings Plans for predictable workloads. These commitments reduce costs by up to 72% compared to on-demand pricing.
Architecture modernisation: with the migration complete, begin the longer-term work of refactoring high-value applications to use cloud-native services — containers, serverless, managed databases, that deliver the performance and cost benefits rehosting alone cannot provide.
Rapyder FinOps — Cloud Cost Optimisation.
Cloud Migration Best Practices
Across hundreds of AWS migration engagements, the same best practices separate successful projects from those that struggle.
Start with your least complex workloads. Early wins build team confidence, validate your process, and create stakeholder momentum that sustains the programme through the harder migrations that follow.
Treat security as a parallel workstream, not a phase. Security design, IAM configuration, and compliance mapping should run alongside architecture design from Day 1. Retrofitting security post-migration is always more expensive and always creates gaps.
Communicate proactively with business stakeholders. Migration projects that fail to communicate cutover schedules, expected downtime, and post-migration changes to business users consistently encounter resistance and delays during the most critical phases.
Engage an experienced AWS partner. Organisations that work with AWS Premier Consulting Partners complete migrations 40% faster and with 25% lower costs on average, according to AWS Migration Acceleration Program data. Rapyder is a Premier AWS Partner with over 460 successful cloud migration engagements.
Frequently Asked Questions
Q: How is the cloud migration process different from cloud adoption?
A: Cloud migration specifically refers to moving existing applications and data from on-premise infrastructure to the cloud. Cloud adoption is the broader organisational journey of building cloud capabilities, culture, and governance, of which migration is one component. Organisations often begin cloud adoption with greenfield projects before undertaking the migration of legacy systems.
Q: What tools does AWS provide for migration?
A: AWS provides a comprehensive suite: AWS Migration Hub (centralised tracking), AWS Application Migration Service (server migration automation), AWS Database Migration Service (database migration with minimal downtime), AWS DataSync (data transfer automation), AWS Transfer Family (file transfer), and AWS Snowball (physical bulk data transfer). AWS Migration Evaluator provides TCO analysis and migration business case modelling.
Q: How do we handle applications that cannot be moved to the cloud?
A: Not every application is suitable for cloud migration at every point in time. Retain on-premise applications that have compliance requirements preventing cloud hosting, that have been recently purchased with long depreciation timelines, or that have performance requirements not yet achievable in the cloud. Revisit retained applications in subsequent migration cycles as cloud capabilities evolve.
Q: What is change data capture (CDC) in database migration?
A: CDC is a technique used by AWS DMS to track and replicate every change, inserts, updates, and deletes, made to the source database after the initial full data load. CDC allows the source database to remain in full production use during migration, with the target database continuously catching up to the source. The cutover window is reduced to the time needed to flush the final CDC transactions.
Q: How do we measure the success of a cloud migration?
A: Measure against the KPIs established in Step 2. Common success metrics include: percentage reduction in monthly infrastructure cost, improvement in application availability (uptime percentage), reduction in time-to-deploy (release velocity), reduction in mean time to recovery (MTTR), and achievement of specific compliance certifications enabled by AWS (ISO 27001, SOC 2, etc.).
Q: What is Rapyder’s Migration Factory model?
A: Rapyder’s Migration Factory is a structured, repeatable migration programme that combines methodology, tooling, and dedicated team composition to deliver AWS migrations in 90-day windows. The model uses wave-based execution, automated discovery and assessment tooling, and a dedicated migration operations centre to maintain velocity across large application portfolios. It has been used to migrate 460+ customers to AWS across BFSI, healthcare, retail, and technology sectors.
Rapyder has completed 460+ cloud migrations across India’s most demanding sectors. Our Migration Factory delivers structured, 90-day AWS migration programmes with dedicated teams and guaranteed outcomes. Begin with a free cloud readiness assessment.
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