The Desktop Transformation Assessment (DTA) forms an integral part of the overall Desktop Transformation Model (DTM) by providing clear guidance on how to turn “Wow” into “How”.  During this series of blog posts, I’m discussing the seven key phases that make up the DTA:

  1. Define Business priorities
  2. Application Assessment
  3. User Segmentation
  4. Capabilities Assessment
  5. High-Level Design
  6. Desktop Transformation Roadmap
  7. High-Level project plan

Now that you’ve determined the key business priorities, analyzed the applications, segmented the users and identified current capabilities you’re ready to start the High-Level Design (HLD).

The HLD outlines the architecture required to support the various desktop and application delivery models identified during the Application Assessment and User Segmentation.  In addition, the HLD should also address the key business priorities captured at the start of the DTA – including requirements for high availability, remote access and business continuity.  Based on the findings from the Capabilities Assessment, a number of existing infrastructure components may be leveraged for the delivery of desktops and/or applications.  Therefore, the HLD should make it clear which components are new and which are already in place.

Despite the clue being in the name, it’s all too easy to forget that the HLD is ‘high-level’ and spend too much time wrapped up in the detail – the time for this will come during the Detailed Design.  The HLD should provide a brief overview of the proposed solution as well as a rough estimate on the infrastructure required.  Start the HLD by creating a high-level architectural diagram that explains how the new desktop and application delivery models will integrate with the existing environment.  I normally divide the diagram up into five different modules – Remote Access, Network Services, Control, Desktop and Imaging as per the XenDesktop Reference Architecture, for example the following diagram shows the key components required to support an XD5 Pooled Desktop solution (existing infrastructure is shaded blue and redundant new infrastructure is shaded green):

Next, provide a brief architectural overview that summarizes each module and explains the function of each key component.  In addition, provide an estimate on the hardware, storage and network infrastructure required per module, for example the following extract provides an overview of the Control Module shown in the diagram above:

Provide an estimate on the total hardware infrastructure required across all modules, for example:


Finally, wrap things up by documenting any design concerns that you might have, for example, insufficient bandwidth, lack of rack space within the data center, etc.

In my next post – Desktop Transformation Roadmap – I’m going to show you how to prioritize the implementation order for the different user groups by comparing their time to value (the amount of time required to implement the chosen FlexCast model within the current environment) against their business value (the importance of the user group to the company).

Andy Baker – Architect
Worldwide Consulting
Desktop & Apps Team
Virtual Desktop Handbook
Project Accelerator