Using the what-if tool, you can plan for an increase or decrease in workload or capacity requirements in your virtual infrastructure. To evaluate the demand and supply for capacity on your resources, and to assess the potential risk to your current capacity, you can create scenarios for adding and removing workloads. You can also determine how much capacity you require to make a migration work. You can run one scenario or group scenarios and run them cumulatively.

Why Create a Scenario

A scenario is a detailed estimation of the resources you must have available in your environment to incorporate upcoming changes. You define scenarios that can potentially add resources to actual data centers. vRealize Operations models the scenario and calculates whether your desired workload can fit in the targeted data center. You can save multiple scenarios for comparison or review.

Committed Scenarios

When you are sure that you need to reserve capacity, you can commit the scenario to have vRealize Operations set aside resources for new, upcoming, or planned workloads. A committed scenario is a supposition about how the capacity and load change on your objects when you change the conditions in your virtual infrastructure environment. You do not have to implement the changes that your committed scenario represents. By committing a scenario, you can determine your capacity requirements before you implement the actual changes.

Why Create a Committed Scenario

In organizations which have separate capacity management and operations teams, committing a scenario helps stakeholders understand the current capacity and upcoming capacity requirements across the board. With committed scenarios, capacity is reserved and this prevents the operations team from performing adhoc resource increase on workloads, while the capacity manager is engaged in resource planning of new projects.

Committed Scenario also helps the team responsible for infrastructure expansion, as it provides actionable insights into future scenarios. In the event capacity becomes limited, it could be accounted for in the expansion.

Where You Find What-If Analysis and Committed Scenarios

What-If Analysis
In the left menu, click Plan > Capacity. The Capacity Plan page opens. On this page, you see options to view or add What-If Analysis scenarios and Committed Scenarios. Click the What-If Analysis tile. and in the What-If Analysis page, click the ADD button to see a list of seven What-If Analysis panes.
Committed Scenarios
In the left menu, click Plan > Capacity. The Capacity Plan page opens. Click the Committed Scenarios pane, and in the Committed Scenarios page, click the ADD button to directly create a committed scenario without first creating a What-If scenario.
The overview tab of the What-If Analysis page has seven panes. Each pane lets you run What-If scenarios to optimize capacity based on the following areas:
  • Workload Planning: Traditional
  • Workload Planning: Hyperconverged
  • Infrastructure Planning: Traditional
  • Infrastructure Planning: Hyperconverged
  • Migration Planning: VMware Cloud
  • Migration Planning: Public Cloud
  • Datacenter Comparison: Private Cloud

How What-If Analysis and Committed Scenarios Work

You can run What-If scenarios to see how much capacity will remain after you add or remove VMs or hosts and add hyperconverged infrastructure (HCI) nodes. Migration planning shows you the capacity and cost information after migrating to cloud based infrastructure.

Scenarios that you save for later are displayed as a list when you browse to Plan > Capacity. You can run, edit or delete the saved scenarios. Use the advanced filter and search box to look for saved scenarios by scenario name, scenario type, datacenter, and cluster. You can select more than one compatible scenarios and run them together. For example, you can create a scenario to remove hosts using the Physical Infrastructure Planning pane, because your organization has hardware that will soon become obsolete. You can create another scenario to add hosts to your physical infrastructure to account for new hardware that will replace the obsolete ones. You can run both these scenarios together to see the capacity after removing old hardware and adding new hardware.

You can only combine scenarios that pertain to the same object. Use the filters in the Plan > Capacity page to narrow down the list based on scenario name, type, data center, or cluster.

You can select the following combinations of scenarios and run them together:

Workload Planning and Physical Infrastructure Planning
  • Add VMs
  • Remove VMs
  • Add Hosts
  • Remove Hosts

The Results Page

The Results page displays the results of running one or more saved scenarios. For Workload and Infrastructure Planning What-If scenarios, the summary page displays the allocation and demand values. If you do not see the allocation values, make sure that the overcommit ratios are activated in the policy. For more information, see the Policy Allocation Model Element topic in the Configuring guide.

To add or remove saved scenarios and run them again cumulatively, click Edit in the Plan > Capacity page. To commit a scenario and reserve capacity, click the COMMIT SCENARIO button. The Create Committed Scenario fly-out opens from the right hand side of the page. Add a name to the scenario you want to commit. Provide and implementation date, and optionally, an end date and click SAVE.