Defining resource constraints
Graphical Scheduling takes CI blackout periods, change windows, and other criteria into account when it looks for a scheduling solution. Considering these resource constraints minimizes the disruption of a Change to your IT infrastructure. To include constraints, you must supply information about blackout periods, change windows, target CIs, and more.
About this task
The following table summarizes the resource constraints that you can define for a scheduling operation. Some of the steps, such as defining CI blackout periods and change windows, are completed when you plan for Changes across your environment and identify times when CIs can safely be changed. You perform other steps, such as specifying target CIs and task owners, when you are scheduling an individual Change.
| Resource constraint | How Graphical Scheduling uses the constraint |
|---|---|
| Change windows and the CIs that can be taken out of service during the Change windows. | Determines the change windows of the target
and impacted CIs for a task, and identifies the intersections among
the change windows. A valid scheduling option is one in which all
of the target and impacted CIs have a change window defined, or where
there is an intersection of the following sets:
|
| Blackout periods and associated CIs. | Takes into account restricted blackout periods, during which caution should be applied in scheduling a Change; and lockdown blackout periods, during which no Change should be scheduled. A valid schedule is one in which tasks are scheduled outside of blackout periods. |
| Target and impacted CIs for each implementation task to be scheduled. | Determines the following:
When this constraint is considered, a valid schedule is one in which there are no other scheduled implementation tasks that have a target or impacted CI that is also a target CI of a task you are scheduling. |
| An owner or owner group for each task to be scheduled, along with work shifts for owners and members of owner groups. | Determines other tasks that are assigned to a task owner, and identifies unassigned time blocks. A valid scheduling option is a time period in which an owner has no other task scheduled. Owner work shifts are also taken into account. |
| Predecessor tasks for each task that is to be scheduled. If a job plan was applied to the Change, this information is associated with the tasks in the job plan. If you have created tasks in addition to those in the job plan, ensure that predecessor tasks are specified. Some tasks do not have predecessor tasks. | If a task has a predecessor task, the predecessor task is scheduled to be started and completed before the following task starts. Successor tasks depend on the completion of their predecessor tasks and cannot be started until after the predecessors have been completed. A valid scheduling option for a task is one that begins after any predecessor tasks complete, and completes before any successor tasks begins. |