What you will learn in this tip: Virtual Desktop Infrastructures (VDIs) have a reputation for being expensive because they have different requirements than
server applications. Learn about VDI costs and get VDI best practices in this tip.
Desktop applications have far different requirements than server applications—server apps are architected and optimized for shared network storage, while desktop apps are not. In addition, desktop apps rely heavily on low-latency built-in/internal storage and are disk IO intensive.
Putting desktop apps in a VDI environment means they will have to deal with additional latency and contention for storage access. This is especially true during boot-up when most users tend to boot-up their desktops at approximately the same time. IT best practices ultimately say to effectively support those virtual desktops with user-acceptable performance requires more expensive shared storage.
To meet those user expectations, that shared storage often has to be what the Evaluator Group calls “highly capable” storage. Highly capable storage is storage that can provide low latency and high IOPS, plus technologies such as solid-state drives (SSDs) with intelligent caching, flexible data placement, and/or data tiering, thin provisioning, wide striping, and read/write time-versioned snapshots. None of this is cheap or free. At the end of the day, shared storage is always more expensive than desktop internal hard disk drives (HDDs) or SSDs. This leads to the inevitable and false conclusion that VDI can never be cost effective for small- to medium-sized businesses (SMBs). But to understand how it can be cost effective requires first understanding the problem VDI solves.
The problems VDI solves
There are numerous problems VDI is designed to solve. VDI noticeably increases desktop uptime and availability. In other words, it eliminates or mitigates the blue screen of death, the frozen cursor or the hourglass that never stops. It does this by centralizing the desktop image and data and just using the processing power of the desktop. It feels like any other workstation to the user while storing nothing locally. This also solves or eliminates a score of other problems such as malware infections, illegal software, and organizational contraband data such as MP3s, videos, or potentially non-compliant materials. It also eliminates the concept of desktop data migration and makes it a lot easier to back up user data.
Solving these problems saves quite a bit of effort, frustration, and possibly money. However, most of those savings are not actually cash expenditures. But better desktop uptime and availability means significantly greater user productivity and easier backups, compliance, data security, among other assets, and that can add up to real savings, too.
Cost-effective VDI strategies
Outside of the cost justifications just mentioned, once again the question for most SMBs is how to they get the benefits of VDI without breaking their IT budget on storage? The answer to that question requires a little bit of “outside-the-box” thinking.
One solution to this conundrum is to use VDI optimization software. This type of software pre-acknowledges writes and some commands, while stacking others, before it gets to the storage system. It is writing to cache instead of disk, essentially spoofing or fooling the OS into thinking the storage system has acknowledged its commands and/or writes before it actually does so.
This VDI enhancement not only reduces the IOPS requirements, it also reduces the amount of shared storage capacity by up to 90% (HDD and SSD), reduces the cost of that capacity, and reduces the number of controllers or systems required to meet VDI performance. The net cost reduction can be as high as 75% putting the cost on a par with or lower than internal drives but with all of the VDI benefits. The only current provider of this type of software today is Atlantis Computing, which works with both Citrix XenDesktop and VMware View.
Another method is to use a shared or clustered file system. A shared or clustered file system can work similarly to VDI optimization. It pre-acknowledges commands and writes before it is committed to the storage system. Cost reduction is on a par with VDI optimization. And just like VDI optimization there is currently only one vendor, Sanbolic Inc. that works with Citrix, Microsoft and VMware.
Finally, consider going one step further. Don’t go halfway and just virtualize the desktop, virtualize the applications, too. Provide only presentation access devices to the users. Utilize the server and virtual server infrastructure to provide all of the application processing. This type of solution requires a mobile device that provides the presentation layer for the application or the ultimate portable thin client computing. Many SMB users are already used to this type of solution. Tablets and mobile smart phones are thin, yet converged, feature-rich devices that function as a presentation layer for applications that are served up from a private cloud (local servers) or public cloud. The application and the data stay in the cloud. This requires modifying the application to run in the private or public cloud. That part is getting easier and easier with tools from Citrix, Microsoft, VMware and even Oracle, as well as startups like Framehawk Inc. This type of thin client computing requires a bit more work up front with an ongoing high payoff in reduced costs, fewer headaches, and increased mobility.
It is possible to make VDI cost-effective for SMBs. It just requires a little bit of imagination.
About the author: Marc Staimer is the founder, senior analyst, and CDS of Dragon Slayer Consulting in Beaverton, OR. The consulting practice of more than 12 years has focused in the areas of strategic planning, product development and market development. With more than 30 years of marketing, sales and business experience in infrastructure, storage, server, software and virtualization, he's considered one of the industry's leading experts. Marc can be reached at firstname.lastname@example.org.
This was first published in August 2011