The biggest risk in cloud migration isn't the technology — it's the approach.
We've guided over a dozen organizations through legacy-to-cloud transitions, and the pattern of failure is always the same: someone decides to move everything at once. Six months and two budget overruns later, the team has lost confidence and the legacy system is still running.
There's a better way. Here's the playbook we use.
Phase 1: Prove the Environment (Weeks 1–4)
Before migrating anything, set up the cloud infrastructure and run it alongside the legacy system. This phase isn't about moving data. It's about answering three questions:
- Can the cloud handle your workload patterns? Replicate peak traffic scenarios and measure response times.
- Do your security and compliance requirements transfer? Map every regulatory control from your legacy audit to the new environment.
- Can your team operate it? Run incident response drills on the cloud stack before it carries real traffic.
This phase costs relatively little and eliminates the single biggest source of migration anxiety: the unknown.
Phase 2: The Strangler Fig (Weeks 5–12)
Named after the plant that gradually grows around a host tree, this pattern routes traffic from legacy to cloud one component at a time. The key principle: start with low-risk, high-visibility wins.
Migration order we recommend:
- Read-only operations first — reports, dashboards, search. Zero risk of data corruption.
- Non-critical write operations — internal tools, admin panels, batch processes.
- Customer-facing features — by this point, your team has weeks of operational confidence.
- Core transaction paths — the final and most sensitive migration, done with full rollback capability.
Each step is a small, reversible change. If something breaks, you route traffic back to legacy in seconds — not hours, not days.
"The best cloud migrations are boring. If your final cutover is exciting, something went wrong in the planning." — Our infrastructure lead
Phase 3: Decommission (Weeks 13–16)
By now, 80–90% of traffic is already running on the cloud and your team has months of operational experience. The final cutover should feel anticlimactic. That's the goal.
Decommission checklist:
- All traffic confirmed on cloud for 2+ weeks with no rollbacks
- Legacy data archived per retention policy
- DNS and load balancer configs cleaned up
- Legacy infrastructure costs stopped
- Post-migration retrospective completed
What Most Guides Won't Tell You
The technical migration is the easy part. The hard part is organizational change management. Your ops team built their careers on the legacy stack. Your compliance team has audited it for years. Moving to cloud means retraining, rewriting runbooks, and — most importantly — giving people time to build confidence in the new system.
Budget 20% of your migration timeline for training and documentation. It's the highest-ROI line item in the entire project.