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This is the 7th part of my VCAP7-DTM Design exam series. In part 6 I covered the creation of a physical network design for Horizon 7. This time we take a look at section 6 of the blueprint, the creation of a physical design for Horizon desktop and pools:

Section 6 – Create a Physical Design for Horizon Desktops and Pools

Objective 6.1 – Design Virtual and Physical Image Masters
Objective 6.2 – Optimize Desktop Images, OS Services and Applications for a Horizon Design
Objective 6.3 – Incorporate Desktop Pools into a Horizon Design
Objective 6.4 – Incorporate RDS Pools into a Horizon Design

The desktops your customer provides must satisfy the use case requirements to ensure a good user experience and user acceptance. To provide desktops with Horizon you have to create so called desktop pools. VMware has a few recommendations and leading practices for the configuration and optimization of a Horizon desktop. These things will help you to enhance the overall scalability and performance of a Horizon implemenation.

Desktop configuration

The desktop build process would look like this:

hroizon desktop build process

  1. You will start with the creation of the target VM
  2. Installation of guest OS
  3. Installation of VMware Tools
  4. Perform image optimization
  5. Installation of globally used applications and Horizon Agent
  6. Creation of VM template

If you understand the customer’s use cases, you will understand what kind of desktops are needed to meet the requirements. The configuration of the desktop VM varies for each pool. The differences between them are often resource allocations like disk size,  installed applications, memory or even the operating system.

For the most use cases VMware recommends only assigning two vCPUs unless it’s proven  and really a requirement to have more CPU power.

Consider RAM reservation settings and keep in mind that high memory settings require more disk space as the VM swap file and the Windows pagefile sizes are related to these settings.

Globally used applications like MS Office or Adobe Reader should be installed within the desktop image. All other applications are delivered with App Volumes, if possible.

OS Optimization

VMware recommends optimizing the guest operating system of a desktop image to positively affect the performance of a Horizon desktop.

Use VMware OS Optimization Tool (OSOT) to optimize your Windows desktops and server images. It is a great tool and will help you to disable OS components  you don’t need and could help to enhance the overall scalability and performance. Make sure you know the optimizations you apply and what settings are changed to avoid any bad user experience or unexpected behaviour of your desktops.

If you are using Windows 10 for example, also make sure that you remove all unneeded native apps.

More details on creation of an optimized Windows image for a Horizon virtual desktop can be found on Tech Zone.

See also the blog article from Login VSI.

Pool Configuration

You can create desktop pools to give users remote access to virtual machine-based desktops. You can also choose VMware PC-over-IP (PCoIP), or VMware Blast to provide remote access to users.

There are two main types of virtual desktop pools.
Automated desktop pools use a vCenter Server virtual machine template or snapshot to create a pool of identical virtual machines.
Manual desktop pools are a collection of existing vCenter Server virtual machines, physical computers, or third-party virtual machines. In automated or manual pools, each machine is available for one user to access remotely at a time.

With Horizon 7.5 a instance is limited to 10’000 desktops and if the planned deployment exceeds this limit, then you must use the Cloud Pod Architecture (CPA) feature. With CPA you can link together 25 pods to provide one big desktop environment for ten geographically distant sites and provide apps and desktops for up to 200’000 sessions. See VMware Horizon 7 sizing limits and recommendations.

In a Horizon design you must state the use cases and use desktop pools which are the logical containers that represent each use case (desktop type, application set, access mode etc.).

With VMware Horizon it is also possible to provide hosted applications with the integration or Remote Desktop Services Hosts (RDSH) based on Microsoft Remote Desktop Services (RDS).
A RDS desktop pool is associated with a farm, which is nothing more than group of RDS hosts. Each RDS host is a Windows Server that can host multiple RDS desktop sessions.

Desktop Persistence

The Horizon 7.5 handbook is a really great source for this part and I will allow myself to copy and past some part of it. 🙂

There are two options for a desktop assignment:

Dedicated-assignment pools
Each user is assigned a particular remote desktop and returns to the same desktop at each login. Dedicated assignment pools require a one-to-one desktop-to-user relationship. For example, a pool of 100 desktops are needed for a group of 100 users.

Floating-assignment pools
Using floating-assignment pools also allows you to create a pool of
desktops that can be used by shifts of users. For example, a pool of 100 desktops could be used by 300 users if they worked in shifts of 100 users at a time. The remote desktop is optionally deleted and re-created after each use, offering a highly controlled environment.

This means that a floating assignment is recommended because it decouples the user from a specific desktop and provides management and resource efficiency. This obviously could also reduce the licensing costs.

Dedicated desktop assignments are useful or required where users have applications or data that they install and keep on a specific desktop. A dedicated desktop can be assigned (fixed) to a specific user or also during the first logon where the next unused desktop will be assigned automatically.

Full Clones, Linked Clones or Instant Clones?

One of the most important questions for your design is whether users need a stateful or stateless desktop to work with. If the user has a stateful desktop, you have to think about the data which needs to be included in a backup (e.g. user profile or application data).

If you provide stateless desktop images you face other challenges. What happens to a user’s profile or data? Should it be saved and be available in the next session?

Stateless desktop images
Also known as nonpersistent desktops, stateless architectures have many advantages, such as being easier to support and having lower storage costs. Other benefits include a limited need to back up the virtual machines and easier, less expensive disaster recovery and business continuity options.

Stateful desktop images
Also known as persistent desktops, these images might require traditional image management techniques. Stateful images can have low storage costs in conjunction with certain storage system technologies. Backup and recovery technologies such as VMware Site Recovery Manager are important when considering strategies for backup, disaster recovery, and business continuity.

There are two ways to create stateless (non-persistent) desktop images in Horizon 7:

  1. You can create floating assignment pools or dedicated assignment pools of instant clone virtual machines. Folder redirection and roaming profiles can optionally be used to store user data.
  2. You can use View Composer to create floating or dedicated assignment pools of linked clone virtual machines. Folder redirection and roaming profiles can optionally be used to store user data or configure persistent disks to persist user data.

There are several ways to create stateful (persistent) desktop images in Horizon 7:

  1. You can create full clones or full virtual machines. Some storage vendors have cost-effective storage solutions for full clones. These vendors often have their own best practices and provisioning utilities. Using one of these vendors might require that you create a manual dedicated-assignment pool.
  2. You can create pools of instant-clone or linked-clone virtual machines and use App Volumes user writable volumes to attach user data and user-installed apps.

Whether you use stateless or stateful desktops depends on the specific type of worker.

There could be a lot more to tell you about when creating desktop pools, but those details can be found on Tech Zone and the available PDFs and Youtube videos.

The next time we take a look at “Section 7 – Incorporate Application Services into a Horizon Physical Design”.