One of the most important aspects of any Horizon design is ensuring that an infrastructure has adequate compute, storage, and network resources to host the required number of virtual desktops. Were it not for troublesome things such as budgets, we could simply purchase an excess of all three of those resources and rest easy at night. In general, our goal is to build an infrastructure that is robust enough to support our average user workload, with some capacity in reserve for growth or maintenance purposes.

Determining the resource requirements of a Horizon environment is a complicated task, and one that could, by itself, fill a book. While it is possible to collect desktop performance data using free tools such as Windows Performance Monitor, gathering all of the data you need would be difficult, and interpreting it even more so. The goal in this section is to introduce you to some tools that were created specifically to help in designing and testing virtual desktop infrastructures, so that you understand exactly what is required to ensure a successful implementation.

The following products can assist in determining your resource requirements and ensuring that your vSphere infrastructure has sufficient capacity and the performance capabilities needed to ensure the desktops perform as expected.

It is important to note that these software packages are typically used as part of a virtual desktop assessment project led by an outside vendor. If your user base has varying requirements, products such as SysTrack and Statusphere FIT may be the only way to find out exactly what infrastructure resources you need to ensure a successful VMware Horizon deployment.

In the event that you choose to determine your own vSphere infrastructure requirements, it is very important to keep in mind the concept of vSphere reserve capacity. I realize that you may choose to do maintenance after hours, so reserve capacity may not be a priority, but what about unplanned downtime, or periods where you can't do maintenance after hours? Many users simply cannot work if they do not have access to their computer, and now that you have virtualized that computer it is your job to ensure it is available whenever it is needed.

Maintaining reserve ESXi server capacity is critical to ensuring that we can accommodate all of our desktops in the event of an ESXi server failure or host maintenance operation. Consider a vSphere cluster with eight ESXi servers hosting 128 desktops each (1024 total desktops):

These calculations assume that we want to protect the ability to provide resources for 100 percent of our desktops at all times, which is a very conservative yet valid approach to building a Horizon infrastructure.

The final configuration of the ESXi servers should take into account not only what percentage of desktops are actually in use at a given time, but also the cost of purchasing the additional capacity needed to support ESXi server failures or other events that require downtime.

In the era of affordable 10 Gigabit Ethernet (GbE) for servers and 1 GbE for desktops I realize that bandwidth within a single site is typically not a concern. The following information is something to keep in mind for clients who are connecting to their Horizon desktop remotely, either from over the Internet or over a WAN from another company site. Ensuring that sufficient bandwidth is available is just another part of making sure your Horizon clients have an acceptable experience when connecting to the Horizon infrastructure.

The VMware document View Architecture Planning (http://www.vmware.com/support/pubs/view_pubs.html) provides some information about how to determine Horizon Client bandwidth requirements. The following table is built upon information obtained from that document as well as other VMware documentation:

Bandwidth utilization is heavily dependent on a number of factors, many of which can be controlled with the Horizon PCoIP GPO settings or even Windows OS settings. Actual bandwidth utilization will vary based on usage and PCoIP settings.

Even with a careful analysis of user desktop usage patterns, it is important to remember that there will be spikes in usage from time to time. A Knowledge or Task Worker who has a need to use an application with a large amount of screen changes, such as viewing images in succession or watching a video, may cause a brief bandwidth spike of between 500 Kbps and 1 Mbps or more. Preparing for these spikes in bandwidth utilization is important in order to preserve the quality of service for all of the Horizon Client connections.

Refer to Chapter 13, Creating a Master Horizon Desktop Image, for information about optimal settings for a Windows desktop, an important topic for those new to virtualizing desktops. Chapter 15, Using Horizon PowerCLI, provides useful information for individuals who prefer to use scripts to automate as many tasks as possible, or simply to try and integrate Horizon with existing infrastructure management platforms.

Up until now, this chapter has been about introducing us to a variety of different concepts that form the basis of architecting our Horizon infrastructure. If we learn anything from this chapter, it is that our goal is to obtain the resources we need to provide an acceptable end user computing experience.

Classifying our end users and measuring their resource requirements is a valuable exercise that will help us understand what will be required to transition our end user computing resources from the desktop to the datacenter. That being said, no amount of planning can possibly replace a properly run pilot that validates not only the configuration of our master Virtual Desktop image, but also the performance of the Horizon infrastructure and the quality of the experience from an end user perspective.

Our Horizon pilot should involve the same types of users as our user analysis did, but not necessarily the same users within each group. The following list includes a number of goals that our Horizon pilot should attempt to achieve: