Citrix App Layering 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.

When the App Layers are attached to a VM at the time of user login, the App Layers specific to a user should be fully attached without adding a significant delay to the logon process. If, for any reason, the App Layering fails or takes more time during the logon process, then the logon process may eventually fail or take longer time to complete. This in turn will impact the productivity of the users and overall user experience with the XenApp server. Therefore, it is imperative that administrators keep track of the time taken for attaching the App Layers. This can be easily done using the Citrix App Layering test.

This test tracks the App Layering process for each user and alerts administrators if any user is experiencing undue slowness during App Layering. This way, administrators are prompted to rapidly initiate remedial measures, so that the bottleneck can be resolved before it seriously impacts a user's productivity and experience. This test also monitors a log file i.e. c:\ProgramData\Unidesk\Logs\ulayersvc.log file created during App Layering process and reports the count of the warning messages and errors occurred. This way, administrators are alerted to the errors and warnings encountered during the App Layering process.


This test reports metrics only when the App Layering feature is enabled for the Citrix XenApp server.

Target of the test : Citrix XenApp Server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for each user connected to the Citrix XenApp that is to be monitored.

This test also reports a set of measures for the Summary descriptor.

Configurable parameters for the test
Parameters Description

Test Period

How often should the test be executed. By default, this is 15 minutes.


The host for which the test is to be configured.


Refers to the port used by the Citrix server .

Report by Domain Name

By default, this flag is set to Yes. This implies that by default, the detailed diagnosis of this test will display the domainname\username of each user who logged into the Citrix server. This way, administrators will be able to quickly determine which user logged in from which domain. If you want the detailed diagnosis to display the username alone, then set this flag to No

Report by Client Name

By default, this flag is set to No. If set to Yes, this test will report metrics for each client machine from which users logged into the XenApp server - i.e., the host name of the client machines will be the descriptors of this test. In this case therefore, the User name column of the detailed diagnosis of this test will indicate the names of the users who logged into the XenApp server.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 6:1. 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.


This measure is not reported for the Summary descriptor.

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.

App Layered disks attached to user session

Indicates the number of App Layered disks attached to this user.


This measure is not reported for the Summary descriptor.

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.

Information messages

Indicates the number of information messages generated during attaching the App Layered disks for the users.


A change in value of this measure may indicate infrequent but successful operations performed by one or more applications.


Indicates the number of information messages generated during attaching the App Layered disks for the users.


A high value of this measure indicates problems that may not have an immediate impact, but may cause future problems.


Indicates the number of errors encountered during attaching the App Layered disks for the users.


A very low value (zero) is desired for this measure, as it indicates that App layering is being performed without any anomalies.

An increasing trend or a high value indicates the occurrence of problems. If so, check the ulayersvc.log for more details.