Organizations considering adopting VDI must exercise caution when choosing the hardware to run their VDI platform.
Virtual desktop performance is directly tied to the performance of the underlying hardware. Although many VDI performance problems can be attributed to inadequate hardware allocations for the individual virtual desktops, hardware selection also plays a major role.
It's important to make sure you tick all the necessary boxes to choose the right VDI hardware for your deployment:
Start with supported hardware
Make sure that the hardware you choose is certified to work with your VDI software. Some of the major vendors actually test various hardware components to make sure they work properly with their VDI software.
For example, Microsoft has a list of hardware components that are certified to work with the Windows operating system. Not every VDI vendor supplies a hardware compatibility list, but if your vendor does then it is imperative to make sure that all of the VDI hardware that you use is from that list. Otherwise, you may find it difficult to receive technical support for any problems that may eventually occur.
Make resources available
There is a big difference between compatibility and performance. If a piece of hardware is listed on a VDI vendor’s hardware compatibility list, then that is a guarantee that the hardware is compatible with the VDI software. There are no guarantees the hardware will perform well enough to support a production workload, however. You must therefore determine what hardware resources your virtual desktops need and make them available.
Plan in fault tolerance
When you're designing and deploying VDI, making sure your hardware is fully fault-tolerant is key. If one of your VDI servers fails you may have a major outage on your hands, unless you have already implemented redundant hardware. It is easy to focus on setting up redundant hypervisors, but you may need redundancy for other VDI components, such as connection brokers or even DNS and DHCP servers.
Buy more than enough
Normally when an organization is getting ready for VDI, the team designing it estimates the resources each virtual desktop will need, then multiplies those resources by the estimated number of virtual desktops they plant to stand up. This method may lead to some performance problems, however, because resource consumption is not linear.
For example, there are certain times of the day when users consume more resources. You must make sure that the hypervisors have sufficient hardware resources to handle the demand of multiple simultaneous logons. Furthermore, some resources will need to be set aside for the hypervisor to use. Like any other software, the hypervisor requires memory, CPU time and storage I/O. At a bare minimum, users should be equipped with at least 20% more resources than the projected requirement.
Remember that redundant hardware does not ensure business continuity. Some people assume that if they run a clustered hypervisor, a node failure will result in virtual desktops failing over to another cluster node. After all, that is how a hypervisor cluster is supposed to work. The caveat to this is that the remaining nodes within the cluster need sufficient resources to absorb the virtual desktops that were running on the failed cluster node.
If there aren't any resources available, the virtual desktops can't fail over, so the nodes that make up a hypervisor cluster must all have sufficient resources to collectively absorb the workload from the failed node. And they still need enough resources in reserve to deliver an acceptable level of performance.
Spend your VDI hardware dollars where they count
Most VDI projects do not come with an unlimited budget, so you must spend money on the resources that are going to make the biggest difference in VDI performance.
Memory, CPU, storage and network are all critical, but if your budget won’t allow you to purchase all your wish list items, then your primary focus should be on high-speed storage and storage connectivity. Storage is usually the biggest bottleneck to VDI performance. While you're at it, it's a good idea to fill your server chassis with as many physical network adapters as it will accommodate. Obviously, memory and CPU resources are important, but in a pinch you can usually get away with low-cost memory and a somewhat modest CPU.
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