What is cloud migration ?

Managing legacy infrastructure drains time and resources that your engineering team could spend shipping features. Cloud migration is the process of moving your applications, databases, and IT workloads from on-premises hardware or colocation centers to a cloud environment. While traditionally associated with leaving physical data centers, today's migrations increasingly involve moving between clouds—often referred to as cloud-to-cloud migration.

Whether you are moving a monolithic application to virtual instances or refactoring services for Kubernetes, migrating to the cloud provides on-demand elasticity, lower maintenance overhead, and predictable infrastructure costs.

This guide covers how cloud migration works, the primary strategies to execute it, common technical challenges, and practical steps to ensure a seamless transition while maintaining European data sovereignty.

What You Will Learn

• The Fundamentals: How cloud migration works step by step.
• The Core Advantages: The real-world benefits of cloud migration, from elasticity to environmental efficiency.
• The 6 Rs Framework: The six primary approaches for moving workloads.
• Practical Insights: Essential cloud migration strategies, common hurdles, and best practices using open tools and Infrastructure as Code.
• Migration vs. Modernization: How simple rehosting differs from building cloud-native architectures.

How cloud migration works

At its core, cloud migration is the process of transferring digital assets such as data, application workloads, IT resources, and databases from an organization's local data centers to a cloud environment, or from one cloud provider to another.

Whether you are performing an on-premise transition or a cloud-to-cloud migration, a successful migration follows a structured lifecycle consisting of four distinct phases:

1. Assessment: Audit your existing IT portfolio. Map out dependencies, network configurations, CPU and RAM utilization, and sensitive data paths.
2. Planning: Select your target cloud architecture, choose your migration strategy, and establish your automation tooling such as Terraform, Ansible, or custom orchestration scripts.
3. Execution: Move data, provision cloud resources, deploy application workloads, and validate system integrity in staging environments prior to switching DNS records.
4. Optimization: Right-size your compute instances, set up automated scaling rules, enforce security policies, and continuously monitor performance and infrastructure costs.

Treating your target infrastructure as code ensures that your cloud environment is reproducible, version-controlled, and easy to audit.

Benefits of cloud migration

Engineering teams are moving away from traditional colocation facilities for reasons that extend far beyond simple convenience. The main benefits of cloud migration include:

Cost Transparency and Efficiency

Replacing heavy upfront capital expenditures in physical server hardware with predictable operational expenditures allows you to pay only for the compute and storage resources you consume. Furthermore, cloud providers with transparent pricing structures and zero egress bandwidth fees eliminate billing surprises.

On-Demand Elasticity and Scalability

Instead of ordering physical servers weeks in advance, you can scale compute nodes, database storage, and Kubernetes worker pools up or down automatically in seconds using web APIs or command-line tools.

High Availability and Resilience

Multi-Availability-Zone deployments, automated snapshot backups, and managed load balancers provide applications with native resilience against localized hardware outages.

Data Sovereignty and Compliance

Migrating to a European cloud provider guarantees full compliance with data protection frameworks like GDPR. Your data remains protected under European jurisdiction, shielded from extraterritorial regulations.

Environmental Efficiency

Modern cloud infrastructure prioritizes energy efficiency. For example, Scaleway's data centers leverage advanced cooling technologies like adiabatic cooling to drastically reduce Power Usage Effectiveness (PUE) and water usage compared to legacy facilities.

Types of cloud migration

When moving application workloads, there is no single universal strategy. Gartner's 6 Rs framework outlines the six primary paths available:

• Rehosting (lift and shift)

• What it is: Moving applications from on-premise physical or virtual machines directly to cloud instances without altering application code or architecture.

• Best for: Legacy systems, tight deadlines, or initial cloud adoption.

• Trade-off: Fast execution, but misses out on cloud-native capabilities like automatic scaling.

• Replatforming

• What it is: Making minor optimizations to application configurations or swapping self-managed components for managed cloud services, such as replacing a self-hosted database VM with a managed PostgreSQL instance.

• Best for: Teams looking to reduce maintenance overhead without rewriting core application logic.

• Refactoring

• What it is: Redesigning and rewriting application components into cloud-native architectures, such as microservices running on managed Kubernetes or serverless functions.

• Best for: High-priority applications that require maximum scalability, resilience, and deployment velocity.

• Repurchasing

• What it is: Replacing a legacy internal software tool or custom application with a cloud-hosted Software as a Service solution.

• Retiring

• What it is: Decommissioning applications, modules, or redundant data stores that no longer deliver business value.

• Retaining

• What it is: Keeping specific applications on-premise due to compliance requirements, ultra-low latency constraints, or unamortized hardware investments.

Cloud migration strategies

Choosing the right cloud migration strategies depends on your workload complexity, internal skill sets, and risk tolerance.

Common cloud migration challenges

While the benefits are significant, the migration journey presents specific technical challenges if not properly planned:

• Data Migration Latency: Moving large volumes of data over standard internet connections can create severe bottlenecks. Encrypted Object Storage and high-bandwidth private network connections help overcome transfer limits.
• Vendor Lock-in: Proprietary cloud APIs can make future platform transitions difficult. Using open-source standards such as S3-compatible Object Storage, standard Kubernetes, and open IaC tools like Terraform mitigates this risk.
• Downtime and Disruption: Improperly synchronized database replication can lead to data loss or prolonged downtime during traffic switchover.
• Secret Sprawl: Hardcoded environment variables and unmanaged credentials create security risks during migration. Secrets should be decoupled from application code during the migration phase using dedicated tools such as Scaleway Secret Manager.
• Cloud-to-Cloud Egress Barriers: In cloud-to-cloud migrations, pulling large volumes of data out of legacy providers often incurs significant outbound bandwidth fees.

Best practices for a successful cloud migration

To ensure a smooth transition, consider the following technical practices:

• Automate Everything with IaC: Declare networks, VPCs, security groups, compute instances, and Kubernetes clusters using Terraform to ensure environment consistency.
• Implement Continuous Replication: Use continuous database replication, such as PostgreSQL logical replication, between on-premise sources and target cloud databases before cutover.
• Decouple Configuration and Secrets: Remove hardcoded credentials from codebases and inject them dynamically at runtime via secret managers.
• Establish Baseline Observability: Set up metrics, central logging, and tracing before migration day to accurately compare performance before and after cutover.
• Design for Cloud Portability: Ensure your architecture relies on open standards to make future cloud-to-cloud transitions frictionless and avoid vendor lock-in.

Cloud migration vs. cloud modernization

While often used interchangeably, migration and modernization represent distinct phases in your infrastructure journey:

Moving a legacy virtual machine to a cloud instance achieves migration. Rewriting that application into containerized microservices running on a managed Kubernetes cluster achieves modernization.

Ready to migrate to Scaleway?

Cloud migration is an infrastructure upgrade that gives your engineering teams the freedom to build, deploy, and scale applications efficiently.

By leveraging open standards, transparent pricing, European data sovereignty, and energy-efficient data centers, Scaleway provides a robust cloud ecosystem without vendor lock-in.

• Set up a production-ready, multi-account foundation with governance and security best practices using Scaleway Landing Zone.
• Explore the Scaleway Documentation for step-by-step guides and tutorials.
• Join the developer community on Scaleway Slack to connect with technical peers and DevRel engineers.