You define scenarios that can potentially add resources to actual data centers. vRealize Operations Manager models the scenario and calculates whether your desired workload can fit in the targeted data center or custom data center.

Where You Find What-If Analysis

From the Home screen, select What-If Analysis under Optimize Capacity in the left pane. From the Quick Start screen, select Plan in the second-from-left column.

How What-If Analysis Works

This feature of Capacity Optimization enables you to forecast successfully the impact of adding a workload to an application. By trying various scenarios, you can arrive at an optimum configuration. Once you select the Add Workload screen, you can choose the exact data center or custom data center where you want to locate the new workload. You can even pick a specific cluster where the workload is to reside.

In choosing the profile of your workload, you have two options:

  • Configure the workload manually by specifying vCPUs, memory, storage, and expected use percentage. You have the further option to click Advanced Configuration and specify more precise characteristics for your workload.

  • Use an existing VM or VMs as templates, importing all the attributes of the selected VMs to your workload scenario. The system allows you to specify how many copies of each selected VM you want to add to the proposed workload.

When you have set the profile for the new workload, enter the start and end date for the period when you want the workload to be active. The default is: starting today and ending three months from today. The system can project scenarios ending up to one year from the current date.

At this point, you can save the scenario to edit or run later on. A list of saved scenarios is available on the What-If Analysis main page. Otherwise, run the scenario to get the vRealize Operations Manager analysis and assessment of your plan.

The system lets you know immediately if the proposed workload fits or does not fit in the suggested location. If it fits, the results list the prime target cluster and any additional possible locations. The system also projects time remaining before the workload runs out of resources. If you select scenario details, the system displays a graphic depiction of resource use. For each attribute value - vCPU, memory, and storage - the amount by which the workload increases the percentage of total application capacity used is shown against a time line. The graph shows the existing percentage used in blue and the total of existing usage and added usage as a percentage of total capacity in green.

If the proposed workload does not fit, the system announces the outcome and provides the following information:

  • How much the added workload reduces the time remaining for the target cluster, for example, from one year to zero.

  • The discrepancy between the space available in the target cluster and what the proposed workload requires, for example, 100 GB of memory.

  • The cost of the workload on the VMware Hybrid Cloud and on the AWS public cloud.

About Clouds

When you run a scenario in the What-If Analysis process, the system provides a recommendation based on the cost of placing the workload on different clouds. This cost-based recommendation varies for different clouds.

The Private Cloud costs are computed based on resource use levels.

For VMware Cloud on AWS, the system displays the resource-use-level cost and the monthly purchase cost for an on-demand subscription. In addition, the system displays the resource-use-level cost and monthly purchase cost for one-year and three-year subscriptions.

Public cloud AWS costs are based on the selected configuration, that is, the allocated resources.

The AWS instance is selected based on the close proximity rule, with simulated resource allocation values. In some scenarios, an exact configuration match is not available in an AWS instance list. Due to this lack of availability, the AWS cost can be inherently higher in comparison.

Table 1. What-If Analysis Page Options

Option

Description

Select

Create a scenario for adding a workload to expand or add an application and determine if new VMs fit in your environment. When clicked, the command displays the Add Workload screen.

Scenario Name

In the heading of the Saved Scenarios table. Checking the box selects all scenarios in the list and turns on the dimmed EDIT and DELETE buttons.

<scenario_name>

Name of a saved scenario. If the scenario has already run, selecting the check box next to a name turns on the dimmed EDIT and DELETE buttons. If the scenario has not run, selecting the check box turns on the dimmed RUN SCENARIO , EDIT, and DELETE buttons.

Filter

Use the filter to search for a specific scenario by name.

Show Columns

Click the small button on the lower left to display the Show Columns dialog box. You can choose up to four columns to display in the table: Scenario Name, Scenario Type, Date Created, and Scenario Start and End Date.