Lessons From Leading Engineering Teams Through Major Migrations

If you've ever led an engineering team through a major system migration, you know the feeling. It's a unique blend of excitement and controlled terror. You're replacing the engine on a plane that's already in the air.

Over my career, I've led teams through several large-scale migrations — from moving $73 million through the Federal Reserve to migrating millions of patient records across healthcare systems. Here's what I've learned.

Start With the Failure Modes

Most migration planning starts with the happy path: "we move data from A to B, validate it, done." That's maybe 20% of the work.

The real planning starts when you ask: what happens when this fails? What happens when it partially fails? What does rollback look like? How do we know if something went wrong three days after we thought we were done?

For the financial migration I led, we designed every single operation to be idempotent. Any step could be re-run safely. We built reconciliation checks that ran at every stage, not just at the end. And we phased the execution over multiple weeks so we could validate each batch before proceeding.

Was it more work up front? Absolutely. But when you're moving $73 million, "we can fix it later" isn't a strategy.

Communication Is the Actual Hard Part

The technical architecture of a migration is challenging. But the communication challenge is harder.

You're coordinating across engineering teams, product, compliance, finance, operations, and often external partners. Everyone has different priorities, different risk tolerances, and different definitions of "done."

What worked for me:

Regular, structured updates that speak each audience's language. Engineers want technical details. Executives want progress and risk summaries.
Explicit decision points where all stakeholders agree before proceeding. Never assume alignment.
Runbooks that document not just what to do, but who does it, when, and what the escalation path looks like.

Your First Plan Is Wrong (And That's Fine)

No migration plan survives contact with reality. You will discover things during execution that you didn't anticipate — data inconsistencies, edge cases in legacy systems, third-party dependencies that behave differently than documented.

The goal isn't to have a perfect plan. It's to have a plan that's adaptable. Build in checkpoints. Design for partial completion. Make sure every step is observable so you can make informed decisions when things go sideways.

Invest in Observability Early

You cannot manage what you cannot see. For every migration I've led, we invested heavily in monitoring and observability before we moved a single record:

Real-time dashboards showing migration progress, error rates, and data validation results
Alerting on anomalies — not just failures, but things that look "off" (unusual counts, timing deviations, validation warnings)
Audit trails that let you trace any record through every step of the migration

This investment paid for itself many times over. When an issue arose (and issues always arise), we could diagnose it in minutes instead of hours.

The Team Matters More Than the Technology

The best migration architecture in the world won't save you if your team isn't aligned, motivated, and clear on their roles. Some things I've learned about leading teams through high-pressure technical work:

Be transparent about risk. Your team can handle hard truths. What erodes trust is being blindsided.
Protect focus. During critical migration phases, shield your team from distractions. Their concentration is your most valuable resource.
Celebrate milestones. Migrations are marathons. Acknowledging progress keeps morale up.
Run retrospectives in real-time. Don't wait until the end. If something isn't working, adapt now.

What I'd Tell My Past Self

If I could go back to my first major migration, I'd say:

Over-invest in reconciliation. You can never have too many checkpoints.
Document decisions, not just designs. Future you needs to know why you chose that approach.
Test the rollback plan. Not in theory. Actually run it. You'll find gaps.
Sleep on it. Fatigue leads to bad decisions. The migration will still be there tomorrow.

Leading teams through high-stakes technical work is one of the most challenging and rewarding things in engineering. The stakes are real, the pressure is real, and when you deliver — the satisfaction is real too.