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Why virtual server tools won't work for VDI performance monitoring

Desktop virtualization isn't synonymous with server virtualization, so VDI performance monitoring demands its own software to track resource usage and balance heavy workloads.

You might be tempted to use the same tools to monitor both virtual servers and virtual desktops, but VDI performance monitoring is a whole different ballgame. Virtual desktops have more dynamic workloads and the end goal is not the same.

Since server virtualization and desktop virtualization are both hypervisor based, you may assume that virtual server monitoring tools will work in virtual desktop infrastructure (VDI), but they almost never do. To get the most accurate data, here's how you should go about virtual desktop performance monitoring.

Why different VDI performance monitoring tools?

There are two main reasons why you need different techniques for VDI performance monitoring. First, the goal behind the monitoring process is different. Virtual machine performance is undoubtedly important, but its main priority is to keep track of physical hardware resource usage. It’s important to know, for example, how much physical memory has been allocated and how much remains available.

Second, most virtual servers handle a relatively unchanging workload. That means you'll need extensive performance monitoring when you first bring the server online, but, unless the server's workload changes, there is little reason to continue aggressively monitoring the performance.

Unlike a virtual server environment, virtual desktop workloads are anything but static. Virtual servers tend to run 24/7, but virtual desktops are powered on and off on an as-needed basis, which means that the demand placed on the underlying hardware is constantly changing. End-user activity such as powering up a virtual machine (VM), logging on, launching an application or playing a video can cause activity spikes at any time.

Plus, in a virtual desktop environment, the goal of VDI performance monitoring is to ensure a positive end-user experience. It’s the end user who drives the virtual desktop performance demand, and each user has different needs. So, it's not safe to assume that two identical virtual desktops will use the underlying hardware to the same extent.

Complexity drives VDI performance monitoring

Another reason you need solid VDI performance monitoring tools is because desktop virtualization tends to be much more complex than server virtualization.

VM performance monitoring consists mainly of the host server's hardware utilization, the disk subsystem (especially if you are using Cluster Shared Volumes) and the network bandwidth usage. With virtual desktop performance monitoring, on the other hand, there are many more components to keep track of. Most VDI offerings use a connection broker that matches end-user requests with individual VMs, for instance, which if left unchecked, can easily create performance bottlenecks.

Another component of VDI that's not typically part of a virtual server environment is licensing servers. A licensing server keeps track of the number of virtual desktops to make sure you don't exceed your license count. You must monitor this server to avoid exceeding your licensing threshold, which could potentially lead to denied user requests.

Though ensuring a positive end-user experience is by far the most important reason for VDI performance monitoring, there is another aspect that's often overlooked: support issues.

Suppose an end user contacts the help desk because he's having a problem with his virtual desktop session. To fix the problem, help desk staff usually needs to know which virtual desktop the user is connected to and which host server that desktop resides on. Performance monitoring tools designed for server virtualization will often pinpoint which host server a VM is running on, but they won't be able to match a user's login to a specific VM. That's why you need VDI-specific performance monitoring tools to identify the user's virtual desktop session.

Software designed to keep tabs on virtual servers is almost always inadequate for virtual desktop performance monitoring, so check into VDI monitoring tools if you haven't already.

About the author:
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. He has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. As a freelance technical writer, he has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies.

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Do you use the same tools to monitor virtual servers as virtual desktops?