Cloud migration is one of the most impactful transformations an organization can undertake. Done well, it reduces costs, improves scalability, and enables faster development. Done poorly, it creates technical debt, security vulnerabilities, and budget overruns. Here's what we've learned from migrating over 50 systems to the cloud.
Assess Before You Migrate
Every successful migration starts with a thorough assessment. Document your current architecture, dependencies, data flows, and performance requirements. Identify which systems are candidates for migration and which might need to stay on-premises.
Not everything should move to the cloud. Some systems have regulatory requirements, latency constraints, or cost profiles that make on-premises hosting the better choice. Be honest about these constraints early rather than discovering them mid-migration.
Choose the Right Migration Strategy
We typically see five migration strategies, often called the 5 Rs: Rehost (lift and shift), Replatform (lift and optimize), Refactor (re-architect), Repurchase (move to SaaS), and Retire (decommission). Each application should be evaluated individually.
Rehosting is fastest but leaves potential cloud benefits on the table. Refactoring unlocks the most value but takes the longest. We often recommend a phased approach: rehost first to reduce data center costs, then optimize over time.
Plan Your Network Architecture
Network architecture in the cloud is fundamentally different from on-premises. Plan your VPC structure, subnet design, and connectivity options carefully. Consider how on-premises systems will communicate with cloud resources during and after migration.
Implement proper network segmentation from the start. Use private subnets for databases and internal services. Set up VPN or Direct Connect for hybrid scenarios. These decisions are hard to change later.
Address Security Early
Cloud security is a shared responsibility. The cloud provider secures the infrastructure; you secure your applications and data. Review your security posture and update it for cloud-specific concerns like IAM policies, encryption at rest and in transit, and network security groups.
Implement the principle of least privilege from day one. Use managed identities instead of long-lived credentials. Enable audit logging for all services. Security incidents in the cloud can spread faster than on-premises, so prevention is critical.
Manage Data Migration Carefully
Data migration is often the hardest part of cloud migration. Large databases can take days to transfer. You need a strategy for minimizing downtime while ensuring data consistency.
We typically use database replication to keep source and target in sync during migration, then perform a quick cutover during a maintenance window. Test your data migration process multiple times before the actual migration day.
Implement Infrastructure as Code
Manual cloud configuration leads to snowflake environments and configuration drift. From the start, manage your cloud infrastructure with tools like Terraform, Pulumi, or CloudFormation. This makes environments reproducible and changes auditable.
Store your infrastructure code in version control and use the same review processes you use for application code. Implement CI/CD pipelines for infrastructure changes so they're tested before reaching production.
Optimize Costs Continuously
Cloud costs can spiral out of control quickly. We've seen organizations spend more in the cloud than they did on-premises because they didn't manage costs proactively. Implement cost monitoring and alerting from day one.
Right-size your resources, use reserved instances for predictable workloads, and implement auto-scaling for variable loads. Review your cloud bill monthly and investigate any unexpected increases. Small inefficiencies compound quickly at scale.
Build Operational Expertise
Operating cloud infrastructure requires different skills than on-premises. Invest in training your team on cloud-native operations, monitoring, and debugging. Don't underestimate the learning curve, especially for teams new to the cloud.
Set up comprehensive monitoring and alerting. Use managed services where possible to reduce operational burden. Create runbooks for common operational tasks and incident response procedures.
Plan for Hybrid Operations
Most migrations don't happen overnight. Plan for a hybrid period where some systems are in the cloud and others are on-premises. This hybrid state can last months or even years for complex organizations.
Ensure your team can operate effectively in both environments. Standardize on tools that work across cloud and on-premises. Plan how you'll handle data consistency and latency during the hybrid period.
Conclusion
Cloud migration is a journey, not a destination. The organizations that succeed are those that plan carefully, execute methodically, and continuously optimize. If you're planning a cloud migration and want to avoid common pitfalls, we'd be happy to share more of what we've learned.