What-If Analysis: Modelling Workload,
Capacity, or Migration Planning
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.
VMware Aria
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
VMware Aria
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 . The Capacity Plan page opens. On this page, you see options to view or add What-If Analysis scenarios and Committed Scenarios. Click theWhat-If Analysistile. and in the What-If Analysis page, click theADDbutton to see a list of seven What-If Analysis panes.
- Committed Scenarios
- In the left menu, click . The Capacity Plan page opens. Click theCommitted Scenariospane, and in the Committed Scenarios page, click theADDbutton 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 and under the
What-If Analysis
or
Committed Scenarios
pages. You can run, edit or delete
the saved scenarios. When you run a scenario, whose start date occurs in the past,
you get a dialog box asking you if you would like to run the scenario with the
current date. If you choose No
, the scenario is not run. If
you choose Yes
, VMware Aria
Operations
runs
the scenario with the current date as the start date. The end date is not affected. 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 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 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
.