What is Change window?
A change window sets when risky work is allowed. It is usually outside business hours, such as an evening or a weekend, or at a time of low traffic for the site. The customer approves the window ahead of time, and everyone involved, such as the engineer, the system owners and the service desk, knows the start time, end time and who decides to stop.
The term varies between organizations. Some use change window for any approved period of change and maintenance window for work on a specific system. Others treat them as the same. There is also the opposite idea, a change freeze, which is a period such as a financial year end during which changes are not allowed. Check which words your organization uses.
A change window is only useful with a plan. A good plan lists the steps, the expected time for each step, a point at which the team will roll back if things go wrong, and the tests that show success. A method of procedure is the usual form for that plan.
How it shows up in practice
- Book the window early, because field engineers and site access need to be arranged to match it.
- Write the plan as a method of procedure with steps, owner, time, rollback point and success tests.
- Confirm site access out of hours: security, building access, and escort arrangements.
- Agree who is on call, who can approve a rollback and who tells users when the work is done.
- Send a report after the window with what was done, what was tested and what is still open.