Cloud Migration

What Is Cloud Migration?

Cloud migration is the process of moving data, applications, computing power and other digital resources from on-premises data centres (or another cloud) to a cloud service provider’s infrastructure. It typically covers applications, databases, development platforms, file shares, identity systems and supporting middleware.

Modern cloud migration is rarely a one-time project — it is a structured programme spanning months or years, broken into waves, governed by an architecture authority and supported by automation. The most widely used framework is AWS’s 6 Rs strategy (Rehost, Replatform, Refactor, Repurchase, Retire, Retain), which gives every workload a clear migration path.

Cloud Migration Definition

Cloud migration is the process of moving data, applications, computing power and other digital resources from local data centres to a cloud service provider’s infrastructure. This can include moving applications, databases, development platforms, and other technologies supporting organisational operations to the cloud.

Common cloud destinations include Amazon Web Services (AWS), Microsoft Azure, Google Cloud Platform (GCP) and Oracle Cloud Infrastructure (OCI). Many enterprises run a multi-cloud or hybrid strategy combining on-premises systems with several cloud providers.

Cloud Migration Security

Cloud migration is a period of elevated risk: misconfiguration, unencrypted data in transit and carrying over legacy vulnerabilities can open the door to attacks. Security should therefore be part of the migration plan from the start (shared responsibility, IAM, encryption).

Key practices include data inventory and classification, encryption during transfer, configuration validation (CSPM) and post-migration security testing. A well-planned migration raises, rather than lowers, the security posture.

How Does Cloud Migration Work?

A typical cloud migration follows several key steps:

1. Discovery and assessment — automated inventory of the existing IT estate (servers, applications, databases, dependencies), business and technical risk analysis, and prioritisation of workloads into migration waves.
2. Cloud provider and landing zone selection — choosing AWS, Azure, GCP or another provider, plus designing the secure foundation: accounts/subscriptions, network architecture, identity, logging, guardrails (AWS Control Tower, Azure Landing Zone Accelerator, GCP Cloud Foundation Toolkit).
3. Migration strategy per workload — assigning each application one of the 6 Rs (see below), based on business value, technical fit and target state.
4. Data and application preparation — refactoring or repackaging where needed, defining cutover plans, preparing data replication (DMS, Azure Migrate, GCP Migrate for Compute Engine).
5. Migration and testing — moving workloads in waves, running parallel testing, performing user acceptance and production validation.
6. Operate and optimise — continuous monitoring, FinOps cost optimisation, security hardening and modernisation roadmap.

The 6 Rs of Cloud Migration

The 6 Rs framework (originated by Gartner, popularised by AWS) defines six possible migration strategies. Most enterprise programmes combine several across the application portfolio:

1. Rehost (“Lift and Shift”) — move applications to cloud VMs with minimal or no code changes. Fastest path, typically 4–12 weeks per app. Trade-off: limited cloud-native benefits, often higher run costs than on-prem.
2. Replatform (“Lift and Reshape”) — small optimisations on the way: replace self-managed databases with managed services (RDS, Azure SQL, Cloud SQL), move to managed Kubernetes, switch to managed message queues. Balances speed with quick wins.
3. Refactor / Re-architect — redesign the application using cloud-native services (containers, serverless, microservices, event-driven architecture). Highest investment, biggest long-term agility and cost benefit.
4. Repurchase (“Drop and Shop”) — replace the existing application with a SaaS product (e.g. legacy ERP → NetSuite, on-prem Exchange → Microsoft 365, custom CRM → Salesforce).
5. Retire — decommission obsolete systems uncovered during discovery (typically part of an enterprise estate is unused or duplicated).
6. Retain (“Revisit”) — leave on-premises for now: compliance constraints, recent infrastructure investment, latency requirements, or applications already scheduled for replacement.

Types of Cloud Migration

Beyond the 6 Rs, cloud migrations are also categorised by source and target:

• Lift and shift migration — moving existing applications and data to the cloud without modification (synonymous with “Rehost”).
• Transformational migration — modernising and optimising applications before or as part of the move (Replatform / Refactor).
• Hybrid migration — combining local and cloud resources in a permanent hybrid model (e.g. compliance data on-prem, web tier in cloud).
• SaaS migration — moving applications to a Software-as-a-Service model where they are delivered as cloud services.
• Cloud-to-cloud migration — moving from one provider to another (e.g. AWS → Azure) or from a single cloud to a multi-cloud architecture.

Benefits of Cloud Migration

Cloud migration delivers several strategic and operational benefits:

• Flexibility and scalability — the ability to adjust resources in real time to changing business needs (autoscaling, on-demand capacity).
• Cost transparency and optimisation — moving from CapEx-heavy data centres to OpEx, with detailed billing and FinOps tooling.
• Higher availability and reliability — multi-AZ and multi-region architectures deliver 99.99% availability without bespoke engineering.
• Faster innovation — managed services (AI/ML, data warehouses, serverless) enable new products in weeks rather than years.
• Stronger security baseline — providers invest billions in security; native services for encryption, identity, threat detection and posture management raise the bar.

Cloud Migration Challenges

Cloud migration also carries real risks:

• Change management — convincing teams, retraining operations and updating processes.
• Security and compliance — keeping up with shared responsibility, GDPR, HIPAA, PCI-DSS and sector-specific regulations.
• Migration costs — initial investment, dual-running during cutover, and surprise data egress charges.
• Integration with existing systems — overlooked dependencies on on-premises directories, file shares, batch jobs and B2B partners.
• Vendor lock-in — proprietary managed services accelerate delivery but raise the cost of leaving.
• Cost overrun in run mode — unoptimised workloads in cloud can cost much more than their on-prem equivalent without right-sizing and reserved capacity.

Cloud Migration Process Stages

1. Assessment and planning — analysis of existing infrastructure, business case, target architecture, programme governance.
2. Preparation — designing landing zones, preparing data and applications, setting up automation pipelines.
3. Migration — moving data and applications to the cloud in waves.
4. Testing and optimisation — validating functionality, performance and security in the cloud, optimising performance and cost.
5. Operate — monitoring, managing and continuously improving cloud resources (FinOps, SRE, security operations).

Best Practices in Cloud Migration

• Detailed planning — invest in thorough discovery; the cost of late-stage surprises is many times the discovery cost.
• Right-size strategy per workload — not every application benefits from refactor; lift-and-shift is fine for stable, low-change systems.
• Security baked in — design landing zones with guardrails, IAM, logging and encryption from day one, not retrofitted.
• Pre-migration testing — staging environments and parallel runs reveal integration issues before users do.
• Team training — operations teams need cloud-native skills (Terraform, Kubernetes, FinOps) before, not after, the cutover.
• Continuous monitoring and optimisation — usage patterns shift quickly; ongoing right-sizing and reserved capacity buying typically save significantly on run costs.

Cloud Migration and Data Security

Data security is a key aspect of cloud migration. It requires layered controls:

• Data encryption — encrypting data in transit (TLS 1.3) and at rest (KMS-managed keys, BYOK for sensitive workloads).
• Identity and access control — enforcing least privilege, MFA on every privileged account, federated identity to corporate directory.
• Regular audits — cloud security posture management (CSPM), regular penetration testing, third-party assessments.
• Compliance management — meeting GDPR, HIPAA, PCI-DSS, ISO 27001, SOC 2 and sector regulations through cloud-native compliance tooling.
• Backup and disaster recovery — multi-region replication, immutable backups, regular DR tests.

Cloud migration is a foundational step in digital transformation, offering flexibility, cost savings and increased resource availability. Success requires careful planning, change management and a security-first mindset.

Learn more

• Radware Cloud Workload Protection — security of workloads in the cloud

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