Optimizing an Image with Microsoft Azure

After you have created your VM, the Windows OS Optimization Tool (OSOT) can assist with the optimization of a Windows image by eliminating settings and disabling features that are unnecessary or detrimental in a virtual environment. You can use this tool after you have added an image, added an image version, or after cloning an image.

Note: Optimization through the Horizon Cloud console is not supported for Linux images. Only Windows-based images can be optimized using OSOT.

Prerequisites

• Verify that the download3.omnissa.com URL is accessible from the VM. This URL must be resolvable and reachable from the management and tenant (desktop) subnets using port 443 over TCP for downloading optimization-related software used in system image optimization operations.

• The Optimization Tool should only be used with the following Windows versions:

  • Windows 10
  • Windows 11
  • Windows Server 2019
  • Windows Server 2022

  Note: Due to an intermittent issue, after deployment of a Windows 11 24H2 operating system into the VM is completed, you must manually restart the VM before running the tool’s Optimize step.

• Ensure that Microsoft Azure Custom Script Extensions (CSE) is not blocked or interrupted by policies, firewalls, or external solutions on the image VM in Microsoft Azure. During the image optimization process for Azure images, Azure Custom Script Extension is used. Therefore, if you use Azure Policy to restrict the installation of extensions on an image VM, which is a VM used for image preparation, do one of the following during the assign-policy phase of the configuration to prevent the optimization process from failing:

  • Ensure that Microsoft Azure security policies related to CSE allow the installation and execution of CSE on the image VM.
  • Allow a CSE whose name contains ‘hcs-image-CustomScriptExtension’ to execute. During the publishing process, Horizon Cloud uses this for the CSE attached to the image VM.

Procedure

1. From the Horizon Cloud console, under Images, select the image you want to optimize.

2. Once selected, a new option under the ... menu will allow you to select Optimize Image.

3. A pop-up appears with more information about optimizing the image using the OS Optimization Tool. Select Optimize to continue.

   Once the image is optimized, you can view the pre-run report and log location by navigating to Monitor > Activity Logs. If the optimization fails, you can see the details of the error message in Activity Logs.

   For more detailed information on manually using the Windows OS Optimization Tool for both Horizon and Horizon Cloud, refer to the Windows OS Optimization Tool for Omnissa Horizon User Guide.