Citrix App Layering.

The Good..............

Think of the Possibilities… There are lots of ways that you can use Citrix App Layering to benefit your workspace delivery strategy, outside of “reducing the number of base images you have to maintain for your non-persistent environment.” Two quick examples:

• Bursting to the cloud, cloud-based DR, and full-on cloud migrations are key business priorities everywhere. The Platform Layer makes it easy to take your on-prem PVS or MCS images to the Cloud without having to separately build and manage them.
• Have a few pesky XenApp silos, each hosting a separate “one-off” app, that are thick-built because you have too few servers in each to justify the extra images you’d have to manage? As long as the applications can be delivered as Elastic Layers, you can deploy the baseline server image with PVS or MCS as a Layered Image and map the right App Layers to the right machine accounts (you can deploy Elastic Layers to users and/or machines) to silo the apps (if you even need to!).

Not All About Image Count. Your business goal is NOT to reduce the number of gold images in your environment, which seems counterintuitive, since image sprawl can be a major operational challenge in any non-persistent environment. But bear with me here. Reducing your image count is one possible technical approach (and really, the only approach afforded by most application layering products) to the underlying business challenge of reducing the total amount of time you spend managing apps and images. With Citrix App Layering, not only is it possible to reduce your image count (and total time managing images) leveraging Elastic Layers, with Layered Images, the images you have take less effort to update and manage (only applying Windows Updates to your OS Layer, only updating antivirus definitions on your antivirus layer, only updating Adobe Reader once in your Adobe Reader layer – you get the idea). In sum, don’t use “image count” as the main measure of success in your Citrix App Layering project, since Layered Images allow you to cut your effort even if you don’t cut your total number of images.

The Bad.........

When starting your App Layering journey, keep these four things in mind to avoid common mistakes:

1. Don’t judge packaging and publishing performance on your PoC environment running on old, slow hardware. Your production environment should be better equipped to handle the IOPS and bandwidth needed for speedy packaging and publishing, and you may end up with a multi-ELM architecture to keep most of that activity local to the data center.
2. Make an extremely clean OS build for import (no optimizations, no customization, no other apps), and hang onto it forever. This can save you from some substantial rebuild work if you run into issues with your OS layer down the road.
3. Citrix App Layering requires very different operational methodology than you may be used to for updating and testing apps and images. Embrace the “App Layering way” and adjust your operational methodology to best fit into the functionality of App Layering rather than trying to fit a square peg into a round hole.
4. Elastic Layering is great but has an associated set of design considerations. Make sure your entire strategy doesn’t hinge on being able to elastically layer the majority of your apps, and don’t measure your success exclusively on image-count reduction.

The Ugly.......

Provisioning Time – This is probably the number 1 complaint 

The whole process takes too long. 

The majority of the steam comes from ‘publishing the image’, whether it’s to PVS or a Hypervisor. If your on XenServer/Hyper-V there aren’t as many conversions since the VM itself is VHD. However, if you run VMware there are conversions that need to happen to go from VMDK to VHD. If you want to test a new version, be prepared to wait 30 minutes. Office isn’t activating? New version and wait 30 minutes. Forgot something? New version and wait 30 minutes. The more layers you have the larger the Image and the longer you’ll have to wait. This goes for adding versions too, not just publishing. When you add a new version it takes a copy of the locally stored OS layer and spins up a new disk on the hypervisor of choice. This all takes time. SSD storage will speed up the process With other tricks....

The future

Many claim that with the rise of cloud computing, application remoting, and SaaS, technologies like application layering will slowly become obsolete. I agree, but it won’t happen immediately—I’m talking about five to 10 years from now. Even then, traditional Windows applications will still be with us and probably so will most of the management challenges we encounter today.

Don’t get me wrong, it’s not like 80% of all companies in the world use app layering (for various reasons). There’s still plenty of room for improvement and future development. Here, I’m thinking about things like ease of use, stability, app compatibility and updates, the layer creation process and the time it takes to do so, and more.

But also think about future developments like Layering as a (cloud) Service, which could be the next step following the current wave of control/management planes in the cloud. Insiders tell me that this will be a reality not too long from now. Will it catch on? Time will tell.

Another interesting development is what both Liquidware and FSLogix are doing today. They offer direct integration with public cloud-based storage (Azure, AWS, Google) through API calls, eliminating the need for an additional Windows Server/SMB share, a very clever way of taking care of things. Use it to store your application layers, in the case of Liquidware, or any other type of data for that matter. Some interesting use cases, besides layering, come to mind.

What’s new and known issues in Citrix App Layering 4.15:

What’s new:

• Support for XenServer 7.6.
• Support for VMware Horizon View 7.6.
• Support for Virtual Apps and Desktops 7 1808, and 7.15 LTSR CU3.
• Support for Citrix Provisioning 1808.
• Support for Windows 10 1803 64-bit, including new installations of Windows 10 1803 Professional, the first time this edition has been supported in App Layering.
• A separate Citrix MCS on Azure connector now exists.
• The XenServer connector has received performance improvements to reduce App Layer version creation times.
• The Hyper-V connector now allows you to choose a template VM.

What’s new and known issues in Citrix App Layering 4 1908:

What’s new:

• Support for Windows 10 1903 as an OS layer.
• Support for VMware Horizon View 7.9.
• You can now manually repair user layer files so that all files and registry settings coming from a specific set of app layers can be made visible again.

Known issues:

• Users cannot sync their OneDrive files when On Demand syncing and elastic layers are enabled. To use OneDrive, On-Demand syncing, include the app in images where elastic layering is not enabled.
• If Windows Defender processes do not start on an app layer created form a Windows 10 1809 OS layer, upgrade App Layering to 19.8 or later, and create a version of the OS layer where the latest Defender security updates are applied.

Additional known issues:

• When using App-V 5.x with Unidesk 4.0.8, VDAs may blue screen.
• Upgrade to Citrix App Layering 4.1 or 4.4+.
• If upgrading 4.0.8 to 4.4, you have to upgrade to 4.3 first as a hop.
• When using App-V 5.x with App Layering 4.2 or 4.3, various issues exist including publishing errors.
• Citrix released a private build (4.3.0.44) which could be obtained by contacting Citrix Support. The fix was then later built in to version 4.4.
• When using PVS and Citrix Workspace Environment Management a conflict in layer priority deletes the Netlogon service dependency on the Norskale Agent Host Service.
• Citrix will address this issue in a future release by making the DependOnService key mergeable. For more information including a workaround see https://www.jgspiers.com/citrix-workspace-environment-manager/#Install-WEM-Agent
• If installing Citrix Receiver including Single Sign-On into an Application Layer, the Citrix Single Sign-on Network Provider will be lost after publishing the image. This is because the Platform Layer (which contains the VDA software) also writes to the Network Provider’s underlying registry REG_SZ key. For a workaround, manually edit the ProviderOrder REG_SZ key within the Platform Layer and insert a value of PnSson.
• When using App Layering Elastic Layers, App-V, and Citrix Profile Management which is configured to delete profiles from the VDA after user logoff, the profiles are never fully deleted.
• Upgrade to App Layering 4.6 and then contact Citrix Support for updated drivers. These drivers should be part of the App Layering 4.7 build when released.
• Office and Windows activation does not work after an upgrade to App Layering 4.5 when Elastic Layering is enabled.
• Upgrade to App Layering 4.6.
• When booting an App Layering image with PVS, you receive a blue screen of death with error: “CvhdMp.sys – SYSTEM_THREAD_EXCEPTION_NOT_HANDLED”.
• Create a second version of the Platform Layer. You don’t have to make any adjustments to the layer, just create a second, publish the image out to PVS and try booting.
• When accessing the ELM through Internet Explorer running on Windows Server, the fonts may not load correctly. To prevent this issue add the ELM FQDN to the Trusted Sites zone.
• When adding a version to your OS Layer, use the same hypervisor that was used originally to build and import that OS Layer.
• When creating an Application Layer use the build-in administrator account to log on. Otherwise RunOnce script will not run and finalisation of the layer will not occur.
• Microsoft Office cannot be made an Elastic Layer due to the way its licenses are integrated with the Windows Store.
• App Layering versions up to 4.9 do not work with the Windows 10 Store. You must therefore disable Store apps. If you have created Application Layers before disabling Store apps, you must recreate those layers.
• If using App Layering 4.10+ you can leave Store Apps enabled.
• Reverting to an ealier version of a Windows 10 OS Layer for example from version 1607 to 1511 will void any User Layers.

For more information :

https://www.citrixguru.com/2019/01/02/best-practices-citrix-applayering/

Thank you :

Dan Morgan

brain madden