Citrix App Layering - OS Test

Citrix App Layering lets you package any Windows application as a virtual disk, layer and deliver it, installation-free, to pooled desktops and session hosts. With App Layering, you can:

  • Install and manage a single copy of your Windows operating system and a single copy of each of your applications in layers. A layer is simply a container for the file system objects and registry entries unique to that layer.

  • Select any combination of layers to create layered Images that are deployable as desktops or session hosts.

  • Deploy the layered images to virtual machine desktops and session hosts, making the applications available to users.

Citrix App Layering enables IT administrators to deliver applications that look, act and feel as if they are installed locally in the VM/Golden Image, but these applications are actually stored as separate manageable objects in their own virtual disks. With Citrix App Layering, any application can be separated from the Windows OS. As a result, IT administrators will only have a single OS Layer to manage regardless of the number of machine configurations (pools, silos, delivery groups). This simplifies the environment while reducing management time/complexity and the costs associated with OS and app management. Application layers can be attached to the virtual machine in one of two ways:

  1. App Layers can be combined with an OS Layer, in a process called image publishing, and pushed to existing provisioning systems such as Citrix Provisioning Services, Citrix Machine Creation Services, or VMware View Composer;

  2. App Layers can be attached to a VM at user login based on user AD group membership and app assignments. Each user can also receive a unique “Personalization Layer." This Personalization Layer will contain unique information for that user that will include things like local Windows profiles, application settings, files and folders created by the user and even user-installed applications.

The App Layers can be attached to persistent and non-persistent desktops in the VDI environment. A persistent virtual desktop, also known as a dedicated desktop, is a unique operating system image created for each user. The customized App Layers are attached to a user when he/she logs in to the persistent desktop at the very first time. These customized layers and specific settings will be available to the user until he/she reboots the desktop. On the other hand, a non-persistent desktop, also called stateless desktop, cannot be personalized for every user and can be shared among multiple users to the environment. The App Layering makes it possible to save user data and user-installed software even in non-persistent deployments. In non-persistent deployments, the App Layers are attached to every user based on their customization whenever he/she logs in. These layers and the corresponding settings will be available until he/she logs off from the session. Once the user logs out from the non-persistent desktop, the layers will be detached and the desktop will be ready for use by another user.

Regardless of the types of virtual desktops to which the App Layering is done, it is important that the App Layers should be fully attached without adding a significant delay to the logon process. If, for any reason, App Layering failed or takes more time during the logon process, then the logon process may fail or take longer time to complete. This in turn will impact the productivity of the users and overall user experience with the virtual server. Particularly, if the users experience frequent delays in the non-persistent environment, then the productivity and experience during every session initiated from the non-persistent desktop will be seriously impacted. Therefore, it is imperative that administrators keep track of the time taken for attaching the App Layers and the layers attached during every user's session. This can be easily tracked using the Citrix App Layering - OS test.

This test helps administrators to promptly find out if there is a delay during the App Layering process and enables them to take remedial measures before the delay causes serious impact on the productivity and user experience.


This test is applicable only for the App Layering enabled desktops that are hosted by the Microsoft Hyper-V VDI server.

Target of the test : A Microsoft Hyper-V VDI server

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each user to the Microsoft Hyper-V VDI server that is to be monitored.

Configurable parameters for the test
Parameter Description

Test period

This indicates how often should the test be executed.


Specify the HOST for which this test is to be configured.


Specify the port at which the target host is listening. By default, this is NULL

Inside View Using

By default, this test communicates with every VM remotely and extracts “inside view” metrics. Therefore, by default, the Inside View Using flag is set to Remote connection to VM (Windows).

Typically, to establish this remote connection, eG Enterprise requires that the eG agent be configured with domain administrator privileges. In high-security environments, where the IT staff might have reservations about exposing the credentials of their domain administrators, this approach to extracting “inside view” metrics might not be preferred. In such environments therefore, eG Enterprise provides administrators the option to deploy a piece of software called the eG VM Agent on every Windows VM; this VM agent allows the eG agent to collect “inside view” metrics from the Windows VMs without domain administrator rights. Refer to Configuring Windows Virtual Machines to Support theInside View Using the eG VM Agent topic for more details on the eG VM Agent. To ensure that the “inside view” of Windows VMs is obtained using the eG VM Agent, set the Inside View Using flag to eG VM Agent (Windows). Once this is done, you can set the Domain, Admin User, and Admin Password parameters to none.

Domain, Admin User, Admin Password, and Confirm Password

By default, this test connects to each virtual guest remotely and attempts to collect “inside view” metrics. Accordingly, the Inside View Using flag is set to Remote connection to VM (Windows) by default. To obtain a remote connection, the test must be configured with the privileges of an administrative user to the domain within which the guests reside. The first step towards this is to specify the DOMAIN within which the virtual guests reside. The Admin User and Admin password will change according to the Domain specification. Discussed below are the different values that the Domain parameter can take, and how they impact the Admin User and Admin Password specifications:

  • If the VMs belong to a single domain:  If the guests belong to a specific domain, then specify the name of that domain against the Domain parameter. In this case, any administrative user in that domain will have remote access to all the virtual guests. Therefore, an administrator account in the given domain can be provided in the Admin User field and the corresponding password in the Admin Password field. Confirm the password by retyping it in the Confirm Password text box.

  • If the VMs belong to different domains: In this case, you might want to provide multiple domain names. If this is done, then, to access the guests in every configured domain, the test should be configured with the required user privileges; this implies that along with multiple Domain names, multiple Admin User names and Admin Passwords would also have to be provided. To help administrators provide these user details quickly and easily, the eG administrative interface embeds a special configuration page. To access this page, simply click on the Click here hyperlink that appears just above the parameters of this test in the test configuration page. To know how to use the special page, refer to Configuring Users for VM Monitoring topic.

  • If the Inside View Using flag is set to ‘eG VM Agent (Windows)’: On the other hand, if the inside view using flag is set to eG VM Agent (Windows), then it implies that the Inside View can be obtained without domain administrator privileges. Therefore, set the Domain, Admin User, and Admin Password, parameters to none.

Report By User

This flag is set to Yes by default. The value of this flag cannot be changed. This implies that the virtual machines in VDI environments will always be identified using the login name of the user. In other words, in VDI environments, this test will, by default, report measures for every username_on_virtualmachinename.

Report Powered OS

This flag becomes relevant only if the report by user flag is set to ‘Yes’.

If the Report Powered OS flag is set to Yes (which is the default setting), then this test will report measures for even those VMs that do not have any users logged in currently. Such guests will be identified by their virtualmachine name and not by the username_on_virtualmachinename. On the other hand, if the Report Powered OS flag is set to No, then this test will not report measures for those VMs to which no users are logged in currently.

Ignore VMs Inside View

Administrators of some high security Hyper-V environments might not have permissions to internally monitor one/more VMs. The eG agent can be configured to not obtain the 'inside view' of such ‘inaccessible’ VMs using the Ignore VMs Inside View parameter. Against this parameter, you can provide a comma-separated list of VM names, or VM name patterns, for which the inside view need not be obtained. For instance, your Ignore VMs Inside View specification can be: *xp,*lin*,win*,vista. Here, the * (asterisk) is used to denote leading and trailing spaces (as the case may be). By default, this parameter is set to none indicating that the eG agent obtains the inside view of all VMs on a Hyper-V host by default.


While performing VM discovery, the eG agent will not discover the operating system of the VMs configured in the Ignore VMs Inside View text box.

Exclude VMs

Administrators of some virtualized environments may not want to monitor some of their less-critical VMs - for instance, VM templates - both from 'outside' and from 'inside'. The eG agent in this case can be configured to completely exclude such VMs from its monitoring purview. To achieve this, provide a comma-separated list of VMs to be excluded from monitoring in the Exclude VMs text box. Instead of VMs, VM name patterns can also be provided here in a comma-separated list. For example, your Exclude VMs specification can be: *xp,*lin*,win*,vista. Here, the * (asterisk) is used to denote leading and trailing spaces (as the case may be). By default, this parameter is set to none indicating that the eG agent obtains the inside and outside views of all VMs on a virtual host by default. By providing a comma-separated list of VMs/VM name patterns in the Exclude VMs text box, you can make sure the eG agent stops collecting 'inside' and 'outside' view metrics for a configured set of VMs.

Ignore WINNT

By default, the eG agent does not support the inside view for VMs executing on Windows NT operating systems. Accordingly, the Ignore WINNT flag is set to Yes by default.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD frequency.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

App Layering duration

Indicates the amount of time taken for attaching the App Layered disks for this user.


Ideally, the value of this should be very low. An increase in the value of this measure may indicate the logon delay for the users.

Have App Layered disks been attached successfully?

Indicates whether/not the App Layered disks have been attached to this user successfully.


The values that this measure can report and their corresponding numeric values are tabulated below:

Measure Value

Numeric value
No 0
Yes 1



By default, this measure reports the above-mentioned Measure Values listed in the table to indicate whether or not the App Layered disks have been attached to this user successfully. The graph of this measure however is represented using the numeric equivalents only.

Use the detailed diagnosis of this measure, to know the revision and name of the layered disks attached to the user sessions and the name of attached files.