Write the cutover on one page before the freeze.
The migration plan is a deck, the freeze is "sometime Saturday," and rollback means "we can switch back." Cutovers tend to fail in the blanks nobody filled, and most of those blanks fit on one page if you write them before the freeze.
Before a system cutover, fill the TWIMCO Cutover Runbook One-Pager: freeze window, dual-run check, named rollback owner, first-hour watch list, and an explicit done-means definition. If any cell is blank, you are not ready to freeze—you are ready to clarify ownership and recovery.
Cutover fails in the blanks
The migration plan is a deck. The freeze is "sometime Saturday." Someone mentions dual-run. Rollback is "we can switch back." The first hour after the cut is unstaffed because everyone is tired. Done is declared when a dashboard looks green.
Cutover fails in the cells nobody filled. Who freezes what. What the dual-run has to prove. Who can roll back. What is watched in the first hour. What done means in the record, not in the chat.
Five cells before you freeze
Freeze. Which writes stop, when, and who is allowed to make an exception.
Dual-run check. What must match, and the person who reads the mismatches. A job that finds differences is not the same as a person who decides what they mean.
Rollback owner. One name. The conditions that make them go back. Not a committee.
First-hour watch. Who is awake, and which signals they watch. Remove the vanity charts before the night starts.
Done. The conditions in the record that mean the cut is over, including which temporary path is supposed to die. A green dashboard is a mood.
If a cell is blank, you are not ready to freeze. You are ready to fill the cell while people are still awake.
How the work moves
Five cells before you freeze
- Freeze window
Start, end, stopped writes, announcer, thaw rule.
- Dual-run check
What must match; who reads; what blocks cut.
- Rollback owner
Named decider, triggers, first steps.
- First-hour watch
Signals, watcher, escalation, notes home.
- Done-means
Record conditions and what remains temporary.
A cutover without a rollback owner is a hope scheduled on the calendar.
Rehearse the first hour
Walk the page once when nothing is on fire. Tired people do not invent a good rollback. They invent a brave one.
Say the freeze out loud: which system still accepts writes, and which does not. If two people disagree, the cell is not done.
Put the page where the people on the night can open it without asking someone for the link.
What the blanks become
Nobody knows which writes still land. The compare job runs and nobody owns the result. Everyone can suggest a rollback and nobody can decide. Dual-write is left on forever because "done" was a feeling.
Those are the incidents the page is for. Fill it for a real cut, not for a template you might use someday.
Sequence of work
Cutover sequence
- T-minus rehearse
Fill one-pager; tabletop rollback; confirm compare owner.
- Freeze
Announce; stop named writes; park arriving work.
- Cut + watch
Execute; first-hour signals; rollback ready.
- Done-means check
Record conditions met; temporary leftover listed.
Put this into practice
Copy the five cells onto one page before the next freeze discussion. Name the rollback owner in the room. Define done as record conditions, including what stays temporary and what must end.
If the cutover is really an ownership and handoff problem, scope it as business process automation.
Related work: Sutton Place.
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