Whether it is Horizon, XenDesktop, or a cloud-based Desktop-as-a-Service provider, the implementation of a virtual desktop and/or published applications environment requires a significant time investment during the design phase.  If care isn’t taken, the wrong design could be put into production, and the costs of fixing it could easily outweigh the benefits of implementing the solution.

So before we move into installing the actual components for a Horizon environment, we’ll spend the next two posts on design considerations.  This post, Part 3, will discuss design considerations for the Horizon virtual desktops, and Part 4 will discuss design considerations for Active Directory.

Virtual desktop environments are all about the end user and what they need.  So before you go shopping for storage arrays and servers, you need to start looking at your desktops.

There are four types of desktops in Horizon 7:

• Full Clone Desktops – Each desktop is a full virtual machine deployed from a template and managed as an independent virtual machine.
• Linked Clone Desktops – A linked clone is a desktop that shares its virtual disks with a central replica desktop, and any changes are written to its own delta disk.  Linked clones can be recomposed when the base template is updated or refreshed to a known good state at periodic intervals.  This feature requires Horizon Composer.
• Instant Clone Desktops – Instant Clone desktops are new to Horizon 7, and they are built off of the VMfork technology introduced with vSphere 6.0.  Instant Clones are essentially a rapid clone of a running virtual machine with extremely fast customization.
• Remote Desktop Session Host Pools – Horizon 6 expanded RDSH support to include PCoIP support and application remoting.  When RDSH desktops and/or application remoting are used, multiple users are logged into servers that host user sessions.  This feature requires Windows Server 2008 R2 or Server 2012 R2 with the RDSH features enabled.

There are two desktop assignment types for desktop pools:

• Dedicated Assignment – users are assigned to a particular desktop during their first login, and they will be logged into this desktop on all subsequent logins.
• Floating Assignment – users are temporarily assigned to a desktop on each login.  On logout, the desktop will be available for other users to log into.  A user may not get the same desktop on each login.

Understanding Use Cases

When you design a virtual desktop environment, you have to design around the use cases.  Use cases are the users, applications, peripherals, and how they are used to complete a task, and they are used to define many of the requirements in the environment.  The requirements of the applications in the type of desktops that are used and how they are assigned to users.

Unless you have some overriding constraints or requirements imposed upon your virtual desktop project, the desktop design choices that you make will influence and/or drive your subsequent purchases.   For instance, if you’re building virtual desktops to support CAD users, blade servers aren’t an option because high-end graphics cards will be needed, and if you want/need full clone desktops, you won’t invest in a storage array that doesn’t offer deduplication.

Other factors that may impact the use cases or the desktop design decisions include existing management tools, security policies, and other policies.

Once you have determined your use cases and the impacts that the use cases have on desktop design, you’ll be able to put together a design document with the following items:

• Number of linked clone base images and/or full clone templates
• Number and type of desktop pools
• Number of desktops per pool
• Number of Connection Servers needed
• The remote access delivery method

If you’re following the methodology that VMware uses in their design exams, your desktop design document should provide you with your conceptual and logical designs.

The conceptual and logical designs, built on details from the use cases, will influence the infrastructure design.  This phase would cover the physical hardware to run the virtual desktop environment, the network layer, storage fabric, and other infrastructure services such as antivirus.

The desktop design document will have a heavy influence on the decisions that are made when selecting components to implement Horizon 7.  The components that are selected need to support and enable the type of desktop environment that you want to run.

In part four, we will cover Active Directory design for Horizon environments.