A layer is a virtual disk where the software for your operating system, platform tools, or one or more applications is installed, or where the user’s data and settings are persisted.
When you create a layer, the App Layering appliance saves the new layer as a virtual disk in your hypervisor environment, and attaches the disk to a packaging machine that it creates.
Once created, each layer is stored in a repository as a virtual disk.
You can create layers for your OS image, your platform tools, and the applications that you want to deliver to users, including:
OS layer, where you install the Windows operating system from ISO. This layer allows you to reuse the same installed OS with all compatible Platform and App layers.
Platform layers, where you install the components of your environment, including the software and settings for your hypervisor, provisioning service and connection broker. By creating a Platform layer for each environment, you can reuse the same OS and App layers in any environment. or example, you can use your other layers in an on-premise environment, such as VMware and a cloud environment, such as Azure.
App layers, where you install applications. Typically, we recommend that you install one app on each layer. If you need an app to be present when another app is installed on a layer, use the Prerequisite option in the Create App Layer wizard. A prerequisite application is present on the packaging disk when you create an App layer or add a version to it.
Layers are assigned to each user as part of the layered image that provisions their desktop. App layers can either be included in the layered image, or delivered individually as an Elastic layer when the user logs onto their desktop.
Elastic layers for app delivery upon login
Elastic layers are App layers that are delivered at logon time rather than as part of a layered image. A single App layer can be delivered either through an image, or elastically.
An App layer cannot be assigned to the same user as both an Elastic layer and as part of the layered image.
Some applications cannot be assigned as an Elastic layer, for example Microsoft Office. To find out whether an application has this limitation, check the App Layering recipes here and in the App Layering forum for notes about layering your application. If no limitations are specified for your application, you should be able to assign it as an Elastic layer.
User layers for persistence of user data
User layers persist user data and settings. A User layer can be automatically created for each user the first time they log onto an image. For this to happen, you must enable the User layers setting for the image template that you use to publish the layered image.