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Cloud Migration — A Strategy That Works

12. 06. 2019 1 min read CORE SYSTEMSai
Cloud Migration — A Strategy That Works

The client came with a request: “We want to go to the cloud.” Sounds simple. Reality: 15 applications, 3 databases, legacy integrations, compliance requirements. We share our migration strategy.

The 6R Framework

AWS recommends 6R: Rehost, Replatform, Repurchase, Refactor, Retire, Retain. For each application, we selected a strategy based on business value and technical debt.

Phase 1: Discovery and Assessment

We mapped dependencies (who calls whom), resource consumption, compliance requirements. AWS Migration Hub + custom scripts for dependency mapping.

Phase 2: Rehost (Lift-and-Shift) for Quick Wins

Legacy applications without active development — move the VM to EC2. Fast, low risk, no code changes. 60% of applications went this route.

Phase 3: Replatform for Key Systems

The main API moved to ECS/Fargate. Database migrated to RDS. Minimal code changes, but significantly better operability — managed services, automatic backups, multi-AZ.

What We Learned

  • Networking first — VPN/Direct Connect must be ready before migration
  • Data migration is always the critical path
  • Test your rollback plan — you’ll need it
  • Stakeholder communication is 50% of the success

Migration Is a Project, Not an Event

The cloud migration took 6 months instead of the planned 3. But the result is worth it — lower operational costs, better availability, faster deployment.

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CORE SYSTEMS

Stavíme core systémy a AI agenty, které drží provoz. 15 let zkušeností s enterprise IT.

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