Analysis: Virtual Desktop Infrastructure

Desktop virtualization is riding the wave of server-consolidation efforts. But is it enterprise ready, and what makes it better than traditional thin-clients?

September 10, 2007

12 Min Read
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It's Monday morning and you're staring down the barrel of 25 desktops that must be set up and shipped to a new remote office by Friday. Sure, imaging tools will help initially, but what about patching and remote management? Information about site security is sketchy, and there are no plans for local IT support to deal with machines mangled with personal files and fragmented drives.

Virtualization has eased many of these issues on servers. Could it work for desktops as well? Short answer, Yes. Vendors are building on the strength of the server virtualization push and coining their offerings Virtual Desktop Infrastructure, or VDI. The idea is big, and as we illustrate in our TCO worksheet, (DOWNLOAD HERE) the value proposition is even bigger: Make your enterprise desktop infrastructure leaner, more secure and easier to standardize, deploy and maintain—all for less than what you're paying now.

VDIClick to enlarge in another window

And use cases go beyond just thin clients for centralizing desktop management and security. Consider one-off or ultra-expensive applications. With VDI, you can deploy oddball OSes or DLLs and strictly manage licensing. Organizations with a focus on security will find that VDI gives IT tight control; you can ensure that any given app is accessed only when and by whom it's supposed to be used.

By Any Other NameVDI isn't much different from server virtualization—abstracting the OS from the hardware and separating multiple instances onto the same physical hardware via a middleware layer, called the hypervisor.

The difference lies in management techniques and features, such as resource pools and connection brokers. For example, the Remote Desktop Protocol, or RDP, enables users to access resource pools or reserved static desktops from physical workstations or terminal devices. And while similar to Citrix or Terminal Services in some respects, VDI replicates a user's desktop experience, isolates users from one another, encapsulates resources for easier management and increases information security.

Immersion Center


Whether you're better off using VDI versus a conventional hosted desktop depends on what you're trying to accomplish. VDI will provide the most benefit if your focus is improving management and centralizing resources. Citrix or another application-centric infrastructure will get you the biggest bang if you're concerned primarily with deploying applications to a large number of users but maintaining few instances. And of course, both can co-exist, each addressing its own niche.

As for vendors, VMware, Hewlett-Packard and IBM all have desktop virtualization plays, as you'd expect. What may be surprising is that Citrix has a story to tell, while Microsoft does not, unless it changes course on Longhorn's virtualization capabilities.

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Build It

Architecturally, an enterprise VDI configuration requires a fast disk subsystem and robust servers to handle hosting; two-way, dual-core boxes with a minimum of 16GB of RAM is a configuration used by VMware as a base to measure capacity and performance of a typical VDI environment.

User access comes via a typical desktop or thin-client terminal plus keyboard, monitor and mouse. Companies such as Neoware (now owned by HP) and Maxspeed Corp. offer mobile thin clients for roaming users. If there's no constant connection to the enterprise mother ship, users can take advantage of disconnected local copies of the virtual desktop object, given a storage mechanism such as USB flash key or external hard drive.

Advanced management tools allow virtual desktops to be "moved" from server to server, and logical resource pools are managed via a connection broker working to answer resource requests, checking machines out and back in again after use. Virtual desktops sit on a shared disk array and are then load balanced over a cluster of host servers. Need less expensive and/or simpler setup? A NAS array or local server disk will suffice for storage.

Impact AssessmentClick to enlarge in another window

With remote deployments, think long and hard before going with an onsite server This introduces additional complexity, and without server redundancy, resource distribution/failover will still need to tie back to your data center. Most companies will be better off truly centralizing the entire effort and deploying only thin clients onsite.

If you have a server virtualization effort under way, virtualized desktops could reside on the same hosts in the short term. In the long run, however, aim to split the two, albeit not necessarily into separate management points. Not only will segregation separate server and desktop I/O and ease management, it will keep your environment organized.

Multifaceted Fun

IT has traditionally had a hard time selling the concept of thin clients to end users, despite much-touted cost savings and the best efforts of vendors. Larry Ellison said during a press conference in March 1996 that "The era of the PC is almost over, and the era of the [thin client] is about to begin." Scott McNealy was also on that bandwagon. More than a decade later, however, thin clients still command only a small fraction of the desktop market, in spite of ever-increasing security concerns and efforts to go green.

Fortunately, VDI goes beyond simply being a desktop replacement or development testbed. For example, desktop virtualization can provide an environment for pesky legacy applications or those requiring odd support models or nonstandard OSes. Apps that rely on a subset of files or drivers that might not play well with others are also prime candidates for VDI, as are desktop environments or applications where high security is a requirement. Resources could be deployed on a "need to know" basis to select employees, and are by default isolated, so accidental access by unauthorized users is unlikely. The same holds true for expensive applications where you want to restrict the number of licenses.Note that the scenarios in which VDI brings security and increased manageability to the table all have one thing in common: isolation. What's Old Is New

VDI as we know it today is not completely novel. Early provider MyWebOS debuted in December 1999 as a free Web-based provider of a simulated desktop environment that included word processing, e-mail and other software; it's since evolved into an online SaaS provider. Other early VDI players, like and Cyrus Intersoft, weren't so fortunate: Each took its turn in the ring but either couldn't compete or was simply ahead of its time. Terminal services and related hosted application platforms survived because they addressed a more immediate need in the marketplace, not to mention that deploying physical desktops has become routine, and therefore perceived as "easier" and "cheaper."

So why now for virtual desktops? It's not only that the server virtualization push has made the concept more palatable. The technology is also solidly vetted out, and more vendors are vying for your virtualization dollar.

VMware is the big name here, and the company has used its celebrity to create the VDI Alliance, an assembly of virtualization and thin-client market powerhouses, to take enterprise virtualization to the next level. Success with server virtualization, and its Virtual Infrastructure 3 product, has granted VMware greater leverage in marketing virtualization's utility.

Still, VMware isn't the only game in town, and it isn't the only one forming alliances. Virtual Iron Software has struck agreements with Provision Networks, storage vendor Compellent Technologies and distributor Tech Data Corp. to target the midsize market with its VDI system. Virtual Iron Enterprise Edition and its Virtualization Manager includes tools, such as LiveMigrate, LiveMaintenance and LiveCapacity, aimed at making VDI easier for smaller shops lacking virtualization specialists, and the company is touting lower costs than VMware—80% lower, to be specific. That's music to the ears of midsize companies seeking a less costly point of entry.Hewlett-Packard, with its Consolidated Client Infrastructure, and IBM are also in the virtualization game, providing end-to-end systems and garnering distribution agreements with other players. And just to keep things interesting, even Citrix is in on VDI, with its Citrix Desktop Server. The jury is still out, though, on Citrix's acquisition of XenSource.

Where's Microsoft? Reports that it will reduce the management functionality of Longhorn virtualization suggest it will not be competitive in enterprise desktop virtualization, for now anyway. We're sure Redmond is watching VDI developments with interest, however.Challenges

As with any fundamental architectural shift, there are considerations beyond the technology at hand. Not insurmountable deal-breakers, just items to note. First off, VDI will change how your organization doles out computing resources—and it's not simply tweaks to under-the-covers IT processes. Users will interact with their desktops differently, especially if you're replacing PCs with thin-client terminals. Additionally, resource-intensive apps may not perform as effectively in a virtual environment.

On the IT side, you'll see workflow changes. VDI won't eliminate desktop maintenance and management, rather, new kinds of workflow and troubleshooting techniques will emerge. And if your organization has separate server and desktop teams, either the server team will inherit much of the workload or you'll need to get your desktop team involved in VDI management.

Other considerations:

• Virtual doesn't mean limitless: the capacity and availability of your deployment is going to depend on your server and storage infrastructure. Knowing what resources you have will help you communicate to end users who may not understand the technology and therefore demand resources beyond the boundary of what's efficient.

• Quantify your resources: Be prepared to calculate the usage and resource allocation of your deployment. Products like V-Kernel, a reporting and chargeback virtual appliance, can help in this regard.

• Get the checkbook out: Initial capital costs could run high if you plan to implement a VDI setup that's fast, redundant, centralized and highly available. Coincidently, the implementation argument could be much harder, especially if no server virtualization efforts are under way, or if your organization's existing infrastructure lacks an enterprise-level build-out, such as robust servers, fast storage and solid WAN pipes. Calculating TCO over three to five years will make the picture brighter.

• Examine your apps: Not all applications work in a VDI environment, but then again, not all apps work in Citrix, either.

Don't think the picture is all negative—here are a few advantages to wet your ROI whistle:

• Everyone in the dynamic resource pool: Your desktop environment can be refreshed anytime; pooled resources of like desktops can be deleted and re-established quickly and easily;

• Mobile users need not be excluded: One major advantage to a fat mobile client is the ability to be offline AND productive. Neoware, and Maxspeed all have mobile thin-client devices, and VMware's PocketACE product enables users to take virtual desktops with them via a portable hard drive, USB flash drive, even an iPod. Yet you still maintain the ability to centralize resources;

• Lower maintenance costs: Regardless of your strategy—workstation replacement, on-demand supplemental desktops or both—the physical element of troubleshooting will be significantly reduced. Remote sites will need fewer visits.

• Longer hardware lifecycle: A typical desktop lease is three years; resource is then replaced or bought at cost. Thin clients can exhibit a much longer lifecycle, be cheaper, and if necessary, more easily replaced;

• Portability: VDI lets you quickly transfer virtual assets—no reinstallation required, unlike migrating an application in a hosted environment;• Quick provisioning: Desktops can be provisioned on-the-fly, copied from a standard resource template; additionally, thin-client hardware can be set up quickly and easily by users;

• Broad OS availability: Multiple operating systems in multiple configurations can be made available for developers and testing;

• Work en masse: Patches, hot fixes and software distribution can be done with little concern about remote-site link speeds or impacting productivity by clogging the byways with "pushes;"

• Secure storage: Desktops can be stored in a "secure" datacenter environment, instead of exposing desktop resources (and potentially sensitive information) to theft and unauthorized distribution.

Getting Your Money's WorthNot surprisingly, big players in the VDI market all tout lower TCO and higher ROI, mainly through improved manageability. Beware though: The complexity of your implementation may introduce challenges in calculating true TCO. Consider beginning with a pilot program in divisions that already have a robust storage infrastructure or have begun a server virtualization effort, where you can piggyback for the short-term.

What's that? You have no ideal area for a phased test deployment? Don't give up on making your case. In our calculations, the numbers just add up. While VMware has not yet released pricing, we estimated that VMware's VDI package with 24x7 support will likely run $18,500 for 25 desktops, and a single, two-way/dual core server will probably cost $9,000. Typical capacity estimates put six to 10 VDs per processor core, yielding 24 to 40 VDs on a single server. Thin clients and KVMs run around $600.

Comparatively, procuring 25 $1,500 desktops yields a lower initial expenditure, but this doesn't take into consideration savings in maintenance, deployment, travel and hardware replacement/rebuilds, to name a few.

All good, but you will need to manage expectations. While a virtual desktop environment does provide a level of on-demand resource allocation, make clear to business users that IT still needs plenty of notice for desktop rollouts. Carefully monitor the capacity and available resources of your VDI installation, and be prepared to add a server or additional VPN or WAN resources.

Bottom line, don't let a VDI deployment get ahead of you. Control is key. Have the infrastructure in place prior to committing resources, and build in extra capacity so that you have room to breathe.Jonathan Berdyck is an NWC and InformationWeek contributor. He manages a team of IT analysts for a healthcare provide based in western Pennsylvania and holds a masters degree from Carnegie Mellon University. He can be reached at [email protected].

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