Introduction:
Migrating to the cloud is one of the most consequential infrastructure decisions a business can make. When done well, it reduces operational costs, improves scalability, strengthens security, and accelerates innovation. When done poorly, it leads to unexpected expenses, downtime, data loss, and months of remediation.
According to HashiCorp's State of Cloud survey, 56 percent of organisations increased their cloud spending in the past year. Yet the Flexera 2025 State of the Cloud Report found that 27 percent of cloud spend continues to be wasted, largely due to poor planning and incomplete migration strategies.
A comprehensive cloud migration checklist is the difference between these two outcomes. This guide provides a practical, step-by-step framework covering pre-migration assessment, execution, and post-migration optimisation.
What Is Cloud Migration?
Cloud migration is the process of moving digital assets — data, applications, workloads, and IT resources — from on-premises infrastructure to a cloud computing environment such as AWS, Microsoft Azure, or Google Cloud Platform. The migration can also involve moving between cloud providers or transitioning from one cloud model to another.
Modern cloud migration is not simply about moving files to someone else's servers. It involves re-evaluating how applications are architected, how data flows through the organisation, and how teams operate in a cloud-native environment. The goal is not just to replicate what exists on-premises, but to take advantage of cloud capabilities that were not available before.
At Codesis Technologies, we work with clients across multiple industries to plan and execute cloud migrations that align with their business objectives and technical requirements (https://www.codesis.tech/product-development).
Pre-Migration Checklist: Planning and Assessment
Thorough planning is the single most important factor in a successful cloud migration. Skipping this phase is the primary cause of cost overruns, timeline delays, and post-migration issues.
Define Your Migration Objectives: Start by answering why you are migrating. Is it to reduce infrastructure costs? Improve scalability? Enhance disaster recovery? Meet compliance requirements? Your objectives will guide every subsequent decision, from choosing a cloud provider to selecting a migration strategy.
Conduct a Complete Infrastructure Audit: Document every server, database, application, and software licence your organisation currently uses. Map dependencies between applications, identify which systems communicate with each other, and note any legacy components that may require special handling.
Assess Cloud Readiness: Not all workloads are equally suited for cloud migration. Evaluate each application against criteria including cloud compatibility, performance requirements, compliance constraints, and business criticality. Tools like AWS Migration Hub and Azure Migrate can automate portions of this assessment.
Choose Your Cloud Provider: Compare AWS, Azure, and Google Cloud against your specific requirements. Consider factors such as existing technology partnerships, regional availability, compliance certifications, pricing models, and the services that each platform offers for your particular workloads.
Establish a Budget and Timeline: Define realistic cost estimates and milestones. Include costs for migration tools, potential downtime, staff training, and the temporary period during which you may run both on-premises and cloud environments simultaneously.
Plan Your Security Framework: Design your security architecture before migration begins. This includes identity and access management, encryption policies, network segmentation, and compliance controls. A cloud migration security checklist should address data residency, access controls, and audit logging requirements.
During Migration: Execution Steps
Start with Low-Risk Workloads: Begin your migration with non-critical applications to validate your process, tools, and team capabilities. A successful pilot migration builds confidence and identifies process gaps before you move business-critical systems.
Migrate Data Carefully: Data migration is the most sensitive phase. Perform incremental data synchronisation between your source and target environments before the cutover. Validate data integrity at every stage using checksums and comparison tools.
Test Thoroughly Before Cutover: Run comprehensive tests including functional testing, performance testing, security testing, and user acceptance testing in the cloud environment before switching production traffic. Establish clear pass/fail criteria for each test.
Execute the Cutover: Switch production traffic to the cloud environment according to your documented cutover plan. Update DNS records, validate network connectivity, confirm firewall rules, and communicate the schedule to all stakeholders. Maintain rollback procedures in case issues arise during cutover.
Validate Post-Cutover: After the switch, monitor application performance, verify data consistency, and confirm that all integrations are functioning correctly. Have the original environment available as a fallback for at least 30 days.
For organisations that are also modernising their software development practices during migration, our guide on Agile methodology in software development (https://www.codesis.tech/blog/importance-of-agile-methodology-in-software-development) provides complementary guidance on aligning development processes with cloud-native delivery.
Post-Migration Checklist: Optimisation and Monitoring
Migration is not complete when the cutover succeeds. The post-migration phase is where organisations realise the full value of their cloud investment — or discover that they have merely moved their problems to a different environment.
Implement Continuous Monitoring: Set up monitoring for application performance, infrastructure health, security events, and cost trends. Tools like CloudWatch (AWS), Azure Monitor, and Google Cloud Operations Suite provide native monitoring capabilities.
Optimise Costs Continuously: Right-size instances based on actual usage data. Implement auto-scaling to match capacity with demand. Use reserved instances or savings plans for predictable workloads. Set up budget alerts to prevent cost surprises.
Decommission Legacy Infrastructure: Once you have confirmed that all migrated workloads are running successfully in the cloud, decommission the on-premises infrastructure. Continuing to run both environments after migration is a common source of unnecessary cost.
Document Everything: Create comprehensive documentation covering the new architecture, operational procedures, security policies, and troubleshooting guides. This documentation becomes essential for onboarding new team members and responding to incidents.
Cloud Migration Strategies: The 6 Rs Framework
AWS popularised the 6 Rs framework for categorising migration approaches. Understanding these strategies helps you choose the right method for each workload:
Strategy | Description | Best For |
Rehost (Lift and Shift) | Move applications as-is to the cloud | Quick migration with minimal changes |
Replatform (Lift and Reshape) | Make targeted optimisations during migration | Adding cloud benefits without full rewrite |
Refactor (Re-architect) | Redesign applications for cloud-native architecture | Maximising cloud capabilities |
Repurchase | Replace with a SaaS or cloud-native alternative | Legacy systems with modern replacements |
Retain | Keep on-premises for now | Systems with compliance or latency constraints |
Retire | Decommission applications no longer needed | Redundant or obsolete systems |
Most enterprise migrations use a combination of these strategies. The key is to evaluate each workload individually and choose the approach that balances business value, risk, and effort.
Cloud Migration Cost Considerations
Cloud migration costs extend well beyond the monthly compute and storage fees. A realistic budget should account for migration tools and services, data transfer costs (especially for large datasets), application refactoring or re-architecting, staff training and certification, temporary dual-environment operating costs, and post-migration optimisation efforts.
One of the most overlooked costs is data egress — the fee charged for transferring data out of the cloud. While moving data into most cloud platforms is free, extracting it can be expensive. Factor this into your long-term cost projections.
"The biggest mistake in cloud migration budgeting is assuming that cloud costs will be lower from day one. The real savings come from optimisation that happens after migration, not during it." — Industry insight
For businesses evaluating how AI can further optimise their cloud operations post-migration, our article on the future of AI in business provides relevant context (https://www.codesis.tech/blog/future-of-ai-in-2026-emerging-trends-reshaping-industries).
Common Cloud Migration Mistakes
Migrating without a clear strategy is the most fundamental error. Teams that begin moving workloads without defined objectives, success criteria, and a documented plan inevitably encounter problems that could have been anticipated.
Underestimating application dependencies leads to broken integrations and unexpected downtime during migration. A thorough dependency mapping exercise during the assessment phase prevents these surprises.
Neglecting security planning until after migration creates vulnerabilities. Security architecture, including identity management, encryption, and network policies, should be designed before any workloads move.
Failing to train staff on cloud-native tools and practices means that the organisation cannot effectively operate in its new environment. Invest in training programmes that cover the specific cloud platform and services your team will manage.
Final Thoughts
A successful cloud migration is methodical, well-documented, and iterative. It begins with clear objectives, moves through careful planning and assessment, executes with disciplined process, and continues with ongoing optimisation after the migration is complete.
The cloud migration checklist in this guide provides a practical framework that scales from small business migrations to complex enterprise transformations. The key is to follow the steps in order, resist the temptation to skip the planning phase, and treat post-migration optimisation as an essential part of the project, not an afterthought. For tailored migration planning and execution support, reach out to the engineering team at Codesis Technologies (https://www.codesis.tech/contact-us).
