Virtual desktop designs tend to overlook two key infrastructure components: Storage responsiveness and wireless network availability and performance. Yet without these two ingredients, VDI is doomed!
VDI Issues? It’s the Storage…
I despise pat answers and rules of thumb, but one truism has emerged from my experience with virtual desktop deployments: Storage I/O performance is by far the most important back-end element. Slow storage doesn’t just mean slow desktops; slow storage means end users will revolt and the project will fail.
Hard disk drives are great at balancing capacity and cost, but performance is not their strong suit. An average hard disk drive is capable only of 100 or so read or write operations per second. This might be enough for a single desktop, but the concentrated I/O demands of virtualization is too much for any drive. Even disk-based storage arrays which offer higher levels of performance can’t keep up with the crush of VDI user demands!
I have never seen a successful VDI implementation without solid state storage as the primary media. Many of the best use PCIe SSDs, SSD RAID, or even RAM for virtual desktop storage I/O, and these work remarkably well. Users of these best-in-class systems are thrilled by improved responsiveness relative to their old desktops. In fact, they’re often as thrilled as users of spinning-disk-based VDI systems are frustrated!
VDI Loves Wireless
Another often-overlooked issue with VDI implementations is the client connectivity. Sure, many offices have decent gigabit Ethernet connectivity to offices and desktops, but what about the newly-mobile, multi-device, BYOD workforce? They need wireless connectivity, and solid, reliable, high-performance Wi-Fi at that!
Deploying a solid Wi-Fi network for VDI isn’t as simple as bolting an access point to the ceiling. Wi-Fi networks must be carefully planned and deployed, since the medium is shared and both physical and radio wave interference can block the signal. And as Keith Parsons recently demonstrated, performance under stress varies dramatically by product.
Even the fastest back-end VDI server will seem slow if clients are using a network that is congested, and they’ll curse just as much if coverage is poor where they need to work. Planning and executing a wireless network is best left to the professionals!
Most devices today support the 802.11n protocol, operating in either 2.4 or 5 GHz. Although rated to perform over 300 Mbps, “wireless n” isn’t anywhere near that speed in most cases. For best results, use 5 GHz with plentiful enterprise-class access points and lots of “backhaul” to reduce congestion. The wireless controller is often just as important as the access points, since this is where access control features live.
Stephen’s Stance
Although I’m obviously glossing over the details of storage and Wi-Fi architecture, I hope you’ve heard my message: Make sure your house is in order before deploying VDI, and focus especially on these two areas! And it pays to bring in a professional to help plan and implement storage and Wi-Fi. Remember – VDI is perilous!
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