With Writable Volumes, you can configure per-user volumes where users can install and configure their own applications and keep the data that is specific to their profile. A Writable Volume is assigned to a specific user and becomes available to the user from any machine.

A Writable Volume is an empty VMDK or VHD file that you assign to a specific user. It mounts to the VM when the user authenticates to the desktop. You can attach only one Writable Volume at a time per-user per OS. For example, if a user logs into a Windows 7 machine and a Windows 10 machine at the same time, one volume is attached to the user on Windows 7 and another one on Windows 10.

A Writable Volume can contain data such as application settings, user profile, licensing information, configuration files, and user-installed applications.

Note: When files and registry entries exist in multiple places, the files and registry entries in Writable Volumes always take precedence over files and registry keys in packages and in the base image.
When a user is allowed to modify, update, or uinstall an application which is either installed on the base image or delivered as an application package, the modified files and registry entries for that application are replicated to the Writable Volume. When the application is removed or unassigned, the modified files continue to remain in the Writable Volume. The files or registry entries that are left over might indicate that the application is available to the end user, however the application does not work. Hence, end users must not be allowed to modify, update, or uninstall an application, which is either installed on the base image or delivered as an application package, from Add or remove programs in the Control Panel. For more information about this protection mechanism, see Uninstalling Applications: This action is not allowed for application <application_name>.

Using App Volumes Manager, you can create, import, edit, expand, and deactivate Writable Volumes.