Optimize image

In the Optimize step of the process, the Windows OS Optimization Tool analyzes the current state of the image VM's Windows operating system by comparing the system to a selected template.

Then you can select the optimization parameters that you want applied to the golden image (golden VM).

The Windows OS Optimization Tool for Horizon contains recommended configurations in the system-provided built-in templates.

Before using the tool and the built-in templates, your IT department should investigate and evaluate the benefits of the various optimizations. There is sometimes a trade-off between productivity and optimization.

Also, to ensure that optimizations do not interfere with other software that might be in use within your organization, you should test both before using the OS Optimization Tool and afterwards.

High-level steps for optimizing with the OS Optimization Tool

Using the tool involves the following steps.

1. If the image is running Windows 11 24H2 or later, ensure that the OS has been restarted at least once since the OS was installed.
2. Before you start, snapshot the golden VM.
3. Ensure the golden VM has the OS Optimization Tool on it, as described in Obtaining the Omnissa Windows OS Optimization Tool for Horizon.
4. Analyze the golden VM (Analyze button).
5. (Optional, recommended) Configure the Common Options settings.
6. Verify that the selected check boxes in the tool's Optimizations pane are your desired optimizations.
7. (Optional) Export the analysis results to an HTML file.
8. Optimize the golden VM (Optimize button).
9. Analyze the optimization results. Each optimization will include the status SUCCESS or FAILED.
10. Troubleshoot any FAILED results: Click the respective FAILED links to review error code and error string information.
11. Address the cause of the failure and optimize again.
12. (Optional) View the optimization history.
13. (Optional) If you want to return a golden VM to its pre-optimized state perform a rollback.
14. (Optional) Create a custom template for use in the OS Optimization Tool, as described in Working with Templates.

Best practices

To make the most of the Windows OS Optimization Tool for Horizon, follow these best practices:

• Prepare the base VM to match the configuration that you plan to deploy for virtual desktops or RDS hosts in your Horizon deployment. This VM should be an unused system. You run the OS Optimization Tool on this base VM.
• (Highly recommended) Take VM-level snapshots before applying any changes so that you can easily revert to the previous state if needed.
• Use the tool on a base image. Apply the tool to an unused system that has been built to match the configuration that you plan to deploy for virtual desktops or RDSH servers.
• Disable as many unnecessary Windows OS components as possible. Consider using the tool's default selected optimizations on a VM where you've disabled such components, and then performing user-acceptance testing (UAT) to see if there are problems. If there are problems, then re-enable any components that cause a problem when disabled.
• Windows 11 24H2: After deploying the Windows 11 24H2 operating system into the VM, manually restart the VM before running the tool's Optimize step. Due to an intermittent issue, if the VM isn't restarted, its system can be in a pending-restart state after optimization, and then later the generalize step can fail.

Unblock executable files

Different versions of Windows 10 have Windows security that prevent executables running and present a warning message Open file – Security Warning. If you see this warning:

• Open the file properties of the tool's EXE file (OmnissaHorizonOSOptimizationTool.exe) and check to see if there is an Unblock option. If there is, select it and apply to make sure that this executable is allowed to run.
• If you copied in SDelete64.exe and LGPO.exe as instructed in the Finalize procedure, unblock these executables.

Windows 11 24H2 Prerequisite

Windows 11 24H2: After deploying the Windows 11 24H2 operating system into the VM, manually restart the VM before running the tool's Optimize step. Due to an intermittent issue, if the VM isn't restarted, its system can be in a pending-restart state after optimization, and then later the generalize step can fail.

Analyze a golden image

After you've completed the high-level steps 1, 2, and 3 outside of the OS Optimization Tool, the next step uses the OS Optimization Tool to analyze the golden image.

These steps describe the process using the tool's UI. The screenshots used here are from version 2503 of the tool.

First you analyze the current state of the golden image, and then later when you optimize, you apply the template's optimizations according to your choices.

1. Start by clicking the Optimize tab.

The System Information section displays the VM OS details. The UI's lower pane prompts for the Analyze button.

This screenshot is based on version 2503 of the tool.

1. Before clicking another button, from the Template menu, select the template you want used in this optimization.

Note: The system-provided built-in template will be selected by default. If you imported any custom templates, you can select your desired template in the Template menu.

You must use a template that matches the OS of the target VM. This point is critical because each OS has different optimizations. If you see an element in the template that is marked with a red X, it is not available in the target image that you are optimizing and the OS Optimization Tool cannot perform that specific optimization.

The following screenshots depict the location of the Template menu and the selected template.

1. Click Analyze to produce a list of optimizations according to the selected template.

• During an Analyze process, the tool checks to see if the golden image has already been optimized with the Windows OS Optimization Tool for Horizon.
• If it has, the previous selections are imported and used instead of the defaults.
• The previous selections are stored in the %ProgramData%\Omnissa\Omnissa OS Optimization Tool\OptimizedTemplateData.json file.
• If you require the default selections instead, delete that %ProgramData%\Omnissa\Omnissa OS Optimization Tool\OptimizedTemplateData.json file, relaunch the tool, and re-run Analyze.

After analysis is completed

After the analysis is completed, the Analysis Summary section in the upper right part of the window displays the optimization state of the target VM.

Detailed optimization information for the targeted system is displayed in the lower part of the window, displaying the optimizations that you can perform.

• Expand the appropriate groups by clicking the arrow next to them and review the sub-tasks and individual optimization settings. The Optimizations column shows a list of selected and unselected items. You'll see a check box before each optimization item, with some check boxes selected and others unselected.

• The selected boxes indicate those items that are included for optimization. By default, some items are not selected for optimization when they can cause undesirable results.

• You can compare the Expected Result column to the Actual Result column. If an item in the two columns is different, it means that parameter has not been optimized.

• Most items have an icon indicating how important it is to optimize.

If the target image has already been optimized with the OS Optimization Tool, previous selections are imported and used instead of default selections. To revert to default selections, first delete the OptimizedTemplateData.json file residing in the Horizon Windows OS Optimization Tool's %ProgramData% area. Then relaunch the tool, and click Analyze again.

Recommendations are grouped into settings and actions.

• Settings include an icon to indicate the importance of optimizing a parameter.
• Those items without an icon are not settings, but actions that will be performed when the optimization is run. The Description column states the action that will be performed.

Analysis Summary pane

The Analysis Summary pane in the upper-right of the main window provides a graphical representation of the current optimization of the targeted system.

The graphical chart makes it easy to review how close the analyzed system is to being optimally configured for best performance in terms of the optimization importance. Within each chart, the number of items in which settings do not match the expected values (red) or which they do match expected values (green) is shown.

Verify the selected optimizations are what you want

Review the list of selected and deselected items to be optimized.

The template chosen will have optimizations selected by default. Adjust the optimizations as appropriate by selecting additional settings or de-selecting settings that were previously selected.

Use the arrow button next to a grouping to expand the group to see any sub-groups and individual optimizations settings. Selecting the check box for a grouping will select all items within that group.

Caution: If the icon next to an item is a blue i, and it has been deselected by the Windows OS Optimization Tool for Horizon, selecting it for optimization can cause instability. Test the optimization of this item before putting it into a production environment.

Note: If the icon next to an item is a green check mark, selecting or deselecting the item will make no difference.

Recommended: Configure the Common Options settings

The Common options button opens a window where you can set preferences for common functions. The Common Options button is only available after you have performed an Analyze.

These options typically involve configuring multiple individual settings. By grouping the actions together, the individual settings get configured as necessary to give the desired outcome.

Changes made in the common options tabs will be reflected in the selection or deselection of individual items in the template. Changes made to common functions overwrite the template setting values for the current optimization run.

Tab - Visual Effect

Settings here control the appearance and performance of Windows visual effects. The selection here influences several individual optimizations. To understand the settings that are affected, in Windows, navigate to System Properties > Advanced > Performance Settings.

Tab - Notification

The setting here deactivates or enables Windows notifications in the VM. This setting applies to various notifications including balloon tips, lock screen messages, security, and maintenance messages. If granular control is required, unselect this option and manually select or deselect the required notification optimizations from the main Optimize window.

Tab - Update

These settings control whether Windows Update functionality is deactivated or left enabled. The default action is to deactivate Windows Update.

Tab - Search

These settings control whether to remove or keep Cortana search. The default is to remove Cortana search. You can also select whether the search item in the taskbar appears as the default box or instead as a magnifying glass icon.

Tab - Store Apps

These settings control removing Windows 10 Store Apps while keeping the commonly used apps. The default behavior is to remove all Windows Store Apps. You can select to keep all apps or select individual apps to be kept.

Note: The Windows Store App itself and the StorePurchaseApp are always retained, regardless of the selection.

Tab - Background

With these settings you can change the default background (wallpaper) to a solid color. Having a solid wallpaper color can have performance benefits, as it can reduce the amount of data the display protocol has to transmit. You can also allow users to change their background.

Tab - Security

With these settings you can select to deactivate or enable various security features in Windows.

Export selections

You can export all of the optimizations that have selected, which allows you to import the selection if you run an optimization again, or to use the same selection on another golden image.

To export the selections:

1. In the lower-right corner of the main window, click Export Selections.

1. Save the JSON file in your preferred location.

To import a saved JSON file, use the Import Selection button, browse to the file and Open.

Export analysis results

Before you optimize the golden image, you can export the analysis results to an HTML file for record keeping and to share with other personnel. You can also compare the analysis results with the post optimization results.

1. In the lower-right corner of the main window, click Export Analysis Result.

1. Save the HTML file in your preferred location.

Important: Do not save the exported analysis reports into a folder belonging to the current user (e.g. Downloads, Documents). Ideally, save these to a network location. This is because when you run a Generalize task, which runs SysPrep, those may get deleted.

Optimize the golden VM

When you are satisfied with the optimizations that you selected in the Optimizations column during the Analyze step, you are ready to perform the optimization.

1. Click the Optimize button at the bottom of the Analyze page.
2. Wait for the optimization to complete, as indicated by the progress bar showing 100% and a new tab being displayed.

Note: When Optimize is run, an export of the optimization selections is created to a default json file. This is %ProgramData%\Omnissa\Omnissa OS Optimization Tool\OptimizedTemplateData.json. If this file is present, this is used during an Analyze to populate the optimization selections.

The new tab shows:

• A new Results tab (active) in the row of Windows OS Optimization Tool for Horizon tabs.
• An Export button to allow you to save the results as an HTML file for later reference. Use Export to save the results as an HTML file for later reference.

View optimization history

Within the OS Optimization tool, you can view the details of the optimization operations that you have performed.

1. Click the History tab.
2. Review the information for the optimization operations that you have performed.

The following table defines the elements that you can view in the optimization history.

Table 2: Optimization history elements

Roll back to the pre-optimized state of the golden image

A rollback attempts to return the golden image to its pre-optimized state. It is advised that you take snapshots before applying any optimizations, as reverting to the snapshot gives a quicker and more reliable method of undoing any undesirable changes.

1. Click the History tab.
2. In the Template Name column, select the check box for the optimized entry that you want to roll back and click Rollback.
3. When the Rollback operation is complete, click OK in the dialog box.

What to read and do next

After optimizing the golden VM, the next step is to generalize the image.