I treat rehearsals like a flight simulator; the real day feels calm when the runbook is familiar. The most stressful cutovers I have seen were the ones where the team “knew” it would be fine. Predictable cutovers come from discipline, not heroics. A migration cutover should feel boring because every step is known, timed, and reversible. When you treat the cutover as a one time event, you increase the chance of downtime and delays.
Build the runbook early and keep it short enough to use under pressure. Every step needs an owner, a precondition, and an expected output. Include commands, dashboard links, and estimated time. If a step has a dependency, call it out explicitly. This is not documentation for later. It is the script you will follow when the clock is running.
Rehearsals that reveal risk: A rehearsal should mirror production as closely as possible. Run the cutover in staging with a full timing pass, and record where manual work is required. Update the runbook after the rehearsal and freeze it before the real cutover. If you change the plan after rehearsal, rehearse again. There is no shortcut.
Rollback needs to be designed, not improvised. Decide what triggers a rollback and who can call it. Keep the rollback path simple and similar to the forward path. Test rollback during rehearsal, not during the live event. It is common for rollback steps to fail when they are not tested.
Define clear exit criteria. When the cutover is done, the team should know which checks must pass before the system is declared stable. Include data consistency checks, backlog depth, and user facing error rates. These checks reduce arguments and prevent premature handoff.
Communication that keeps focus: Pick a single status channel and post updates at fixed times. Communicate the maintenance window, expected risks, and impact clearly. This reduces side conversations and lets engineers focus on the steps. If you have stakeholders outside engineering, designate one person to handle them.
During the cutover, track time against the runbook. If a step takes longer than expected, call it out early. This makes it easier to decide whether to continue, pause, or roll back. A reliable cutover is a practiced routine. The time you spend on runbooks and rehearsal pays for itself the moment you avoid an unplanned outage.
Make every cutover step observable. If you cannot confirm that a step succeeded, the runbook is not complete. Add simple checks like service health endpoints, queue depth, or database replication lag so the team can see progress in real time. Avoid last minute configuration changes. Freeze versions and settings well before the cutover. If you must change a setting, update the runbook and revalidate it. Stability comes from reducing the number of moving parts during the maintenance window.
After the cutover, schedule a stabilization period with clear monitoring goals. Use that window to fix small issues before teams move on to the next wave. Stabilization is often where hidden problems are found, not during the cutover itself.
Example rehearsal: a cutover rehearsal plan
A migration cutover is safest when rehearsed. A week before the cutover, run a rehearsal in staging that mirrors production traffic patterns. Use the same runbook, the same monitoring dashboards, and the same communication plan. Record the time for each step and note any surprises. On cutover day, the team follows the updated runbook and uses the rehearsal timings to decide whether the plan is still on track.
Cutover mistakes to avoid
- Skipping rehearsals because the team feels confident.
- Having a rollback plan that no one has tested.
- Failing to coordinate DNS changes and cache invalidation.
- Lack of a communication plan for stakeholders and support.
- Allowing unrelated changes during the cutover window.
Cutover checklist
- Write a runbook with step owners and expected durations.
- Rehearse the cutover in a staging environment.
- Define clear go or no go criteria before starting.
- Lock changes during the cutover window.
- Prepare rollback steps and test them in advance.
- Communicate status updates on a fixed cadence.
Data migration strategy: Cutovers often fail because data migration is treated as an afterthought. Define how data moves, how you verify it, and when you stop writes to the old system. If you need dual writes, define how long they last and how you resolve conflicts. Use a validation checklist that compares row counts, checksums, and spot checks of critical records. This keeps data integrity from being a guess.
Stakeholder roles: Clear roles reduce chaos. Identify a cutover lead, a communications owner, and a rollback owner. Give each role a decision threshold. For example, the rollback owner can trigger rollback if latency exceeds a defined limit for more than 10 minutes. These thresholds keep decisions fast when pressure is high.
Freeze and data sync window: Define a short freeze window where no unrelated changes are allowed. This reduces the variables during cutover. If you need a data sync window, communicate it in advance so teams know when writes will pause. Even a 15 minute window can prevent data conflicts.
