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.

Note:

This test is applicable only for the App Layering enabled desktops that are hosted by the ESX server host.

Target of the test : An ESX server host

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each user to the virtual server that is to be monitored.

Configurable parameters for the test:
Parameter Description

Test Period

How often should the test be executed

Host

The host for which the test is to be configured

Port

The port at which the HOSTlistens. By default, this is NULL.

ESX user and ESX password

In order to enable the test to extract the desired metrics from a target ESX server, you need to configure the test with an ESX USER and ESX PASSWORD. The user credentials to be passed here depend upon the mechanism used by the eG agent for discovering the VMs on the target ESX server and collecting performance statistics from it. These monitoring/discovery methodologies and their corresponding configuration requirements have been discussed hereunder:

  • VM discovery using the web services interface of the ESX server: Starting with ESX server 3.0, a VMware ESX server offers a web service interface using which the eG agent discovers the guest operating systems on a physical ESX host. The VMware VI SDK is used by the agent to implement the web services interface. To use this interface for discovering the VMs, this test should be configured with an ESX USER who has “Read-only” privileges to the target ESX server. By default, the root user is authorized to execute the test. However, it is preferable that you create a new user on the target ESX host and assign the “Read-only” role to him/her. The steps for achieving this have been elaborately discussed in Creating a New User with Read-Only Privileges to the ESX Server.

    ESX servers terminate user sessions based on timeout periods. The default timeout period is 30 mins. When you stop an agent, sessions currently in use by the agent will remain open for this timeout period until ESX times out the session. If the agent is restarted within the timeout period, it will open a new set of sessions. If you want the eG agent to close already existing sessions before it opens new sessions, then you would have to configure all the tests with the credentials of an ESX user with permissions to View and Terminate Sessions. To know how to grant this permission to an ESX user, refer to Creating a Special Role on an ESX Server and Assigning the Role to a New User .

  • VM discovery using the vCenter in the target environment: By default, the eG agent connects to each ESX server and discovers the VMs executing on it. While this approach scales well, it requires additional configuration for each server being monitored. For example, separate user accounts may need to be created on each server for read-only access to VM details. While monitoring large virtualized installations however, the agents can be optionally configured to perform guest discovery using the VM information already available in vCenter. In this case therefore, the ESX USER and ESX PASSWORD that you specify should be that of an Administrator or Virtual Machine Administrator in vCenter. However, if, owing to security constraints, you prefer not to use the credentials of such users, then, you can create a special role on vCenter with ‘Read-only’ privileges.

Refer to Assigning the ‘Read-Only’ Role to a Local/Domain User to vCenter to know how to create a user on vCenter.

If the ESX server for which this test is being configured had been discovered via vCenter, then the eG manager automatically populates the ESX USER and ESX PASSWORD text boxes with the vCenter user credentials using which the ESX discovery was performed.

Like ESX servers, vCenter servers too terminate user sessions based on timeout periods. The default timeout period is 30 mins. When you stop an agent, sessions currently in use by the agent will remain open for this timeout period until vCenter times out the session. If the agent is restarted within the timeout period, it will open a new set of sessions. If you want the eG agent to close already existing sessions before it opens new sessions, then you would have to configure all the tests with the credentials of a vCenter user with permissions to View and Terminate Sessions (from vCenter 4.1, this is called the View and stop sessions permission). To know how to grant this permission to a user to vCenter, refer to Creating a Special Role on vCenter and Assigning the Role to a New User. When the eG agent is started/restarted, it first attempts to connect to the vCenter server and terminate all existing sessions for the user whose credentials have been provided for the tests.

This is done to ensure that unnecessary sessions do not remain established in the vCenter server for the session timeout period.  Ideally, you should create a separate user account with the required credentials and use this for the test configurations. If you provide the credentials for an existing user for the test configuration, when the eG agent starts/restarts, it will close all existing sessions for this user (including sessions you may have opened using the Virtual Infrastructure client). Hence, in this case, you may notice that your VI client sessions are terminated when the eG agent starts/restarts.

Confirm password

Confirm the password by retyping it here.

SSL

By default, the ESX server is SSL-enabled. Accordingly, the SSL flag is set to Yes by default. This indicates that the eG agent will communicate with the ESX server via HTTPS by default. On the other hand, if the eG agent has been configured to use the VMPerl API or CLI for monitoring (i.e., if the ESX USER parameter is set to none), then the status of the SSL flag is irrelevant.

Like the ESX sever, the vCenter is also SSL-enabled by default. If you have chosen to use the vCenter for monitoring all the ESX servers in your environment, then you have to set the SSL flag to Yes.

Webport

By default, in most virtualized environments, the ESX server and vCenter listen on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled ESX server directly, the eG agent, by default, connects to port 443 of the ESX server to pull out metrics, and while monitoring a non-SSL-enabled ESX server, the eG agent connects to port 80. Similarly, while monitoring an ESX server via an SSL-enabled vCenter, the eG agent connects to port 443 of vCenter to pull out the metrics, and while monitoring via a non-SSL-enabled vCenter, the eG agent connects to port 80 of vCenter. Accordingly, the WEBPORT parameter is set to 80 or 443 depending upon the status of the ssl flag.  In some environments however, the default ports 80 or 443 might not apply. In such a case, against the WEBPORT parameter, you can specify the exact port at which the ESX server or vCenter in your environment listens so that the eG agent communicates with that port.

Virtual Center

If the eG manager had discovered the target ESX server by connecting to vCenter, then the IP address of the vCenter server used for discovering this ESX server would be automatically displayed against the VIRTUAL CENTER parameter; similarly, the ESX USER and ESX PASSWORD text boxes will be automatically populated with the vCenter user credentials, using which ESX discovery was performed.

If this ESX server has not been discovered using vCenter, but you still want to discover the guests on the ESX server via vCenter, then select the IP address of the vCenter host that you wish to use for guest discovery from the VIRTUAL CENTER list. By default, this list is populated with the IP address of all vCenter hosts that were added to the eG Enterprise system at the time of discovery. Upon selection, the ESX USERand ESX PASSWORD that were pre-configured for that vCenter server will be automatically displayed against the respective text boxes.

On the other hand, if the IP address of the vCenter server of interest to you is not available in the list, then, you can add the details of the vCenter server on-the-fly, by selecting the Other option from the VIRTUAL CENTER list. This will invoke the ADD VCENTER SERVER DETAILS page. Refer to Adding the Details of a vCenter Server for VM Discoverysection to know how to add a vCenter server using this page. Once the vCenter server is added, its IP address, ESX USER, and ESX PASSWORD will be displayed against the corresponding text boxes.

On the other hand, if you want the eG agent to behave in the default manner -i.e., communicate with each ESX server for monitoring and VM information - then set the VIRTUAL CENTER parameter to ‘none’.

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 VMs inside view

Administrators of some high security VMware 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 an ESX host by default.

Note:

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.

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.

Inside view using

By default, this test obtains the “inside view” of VMs using the eG VM Agent. Accordingly, the inside view using flag to eG VM Agent by default. The eG VM Agent is a piece of software, which should be installed on every VM on a hypervisor. Every time the eG agent runs this test, it uses the eG VM Agent to pull relevant 'inside view' metrics from each VM. Once the metrics are collected, the eG agent then communicates with each VM agent and pulls these metrics, without requiring administrator privileges. Refer to Configuring the Remote Agent to Obtain the Inside View of VMs for more details on the eG VM Agent.

Domain, Admin User, and Admin Password, and Confirm Password

By default, these parameters are set to none. This is because, by default, the eG agent collects 'inside view' metrics using the eG VM agent on each VM. Domain administrator privileges need not be granted to the eG agent if it uses this default approach to obtain the 'inside view' of Windows VMs.

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 USERflag 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.

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, 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.

Seconds

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

Note:

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.