Maintenance window
An agreed time, usually when few people use the systems, set aside for planned changes that may affect a service.
Also written change window, planned outage, service window
A maintenance window is a regular, agreed time for planned work that could interrupt a service. On a mainframe, that might be applying maintenance and IPLing a system, upgrading a subsystem or making a large change to a database.
Windows are usually at quiet times, such as early on a Sunday morning, and they are agreed with the business and often announced to customers. Work that needs one is planned in detail, with steps, timings and a way to back out if something goes wrong, so the service is back before the window closes.
Mainframe sites try hard to need fewer windows. With a sysplex, many changes can be made one system at a time while the others keep the service running, so customers see no interruption. That is part of why mainframe services can have such high availability.
The term is close to batch window but different. The batch window is when batch runs every night. A maintenance window is when changes are allowed to interrupt service.
Where can I learn this hands-on?
Right here, at ZedBank. You take a junior job at a simulated bank and learn each part of the work by doing it, with Zed beside you. There's nothing to install.
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- Change controlThe process every change goes through before reaching production: reviewed, approved, scheduled and reversible.
- IPLInitial program load: starting z/OS on a system, the mainframe word for booting.
- Change freezeA period when no changes may be made to production systems, except emergencies, to protect a busy or important time.
- SLAService level agreement: an agreed target for a service, such as how available it must be or by what time a batch run must finish.
- Batch windowThe period, usually overnight, in which batch work has to finish before the business needs the systems back.