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From A to Xen: Your options for virtual desktops

What are the options for virtual desktops? From Citrix to Microsoft, learn about some of the emerging players in the field and what an IT manager should know about them.

With workers freeing themselves from the chains of a single desk and companies expanding operations to far corners of the world, surely desktop virtualization -- and, more specifically, a virtual desktop infrastructure (VDI) -- has crossed your mind.

Jonathan Hassell

With a VDI, desktop computers used by clients are virtualized and stored on central terminal servers. Users connect to a terminal server via a connection broker, which then distributes user connections to the appropriate virtual machine. All settings, programs and data are stored within each machine so users can get the same consistent working environment on virtual desktops -- regardless of where they are connecting from or what client device they are using.

VDI is certainly gaining in popularity, and the products and tool sets for managing VDI setups are improving as well. But what are the options for midsized organizations considering virtual desktops? Let's take a look at the major and emerging players in this space:

Citrix XenDesktop: Citrix Systems Inc. has been at the forefront of presentation virtualization for years, and its XenDesktop and XenServer products are taking the company's story deeper into the layers of virtualization. Citrix products use the ICA protocol, rather than a remote desktop protocol, to stream virtual desktops to clients, and in some tests ICA-based products have performed better under severe network loads and significant latency than RDP-based products.

You can get started fairly easily -- build out a base virtual desktop using XenServer, move it to a provisioning server that can launch both static and pooled virtual desktops and hand them out to users via the Desktop Delivery Controller. Of course, while the XenServer piece of the puzzle is free from Citrix, XenDesktop isn't and carries a minimum $75 fee for each concurrent user.

Microsoft Virtual Desktop Infrastructure: Microsoft slipped in the back door a bit in regards to virtual desktop infrastructure, but it indeed has all the core pieces necessary to support a VDI solution. In particular, Microsoft offers a VDI connection broker called Remote Desktop Connection Broker, included in Windows Server 2008 R2. In conjunction with Hyper-V, RD Connection Broker lets you construct pools of virtual desktops or link Active Directory users to their own personal virtual desktops. But that's about it as far as features go.

Since Microsoft is new in this space, the current R2 release is essentially just a foundational VDI offering. Microsoft recommends Citrix XenDesktop for companies seriously considering a VDI implementation. But the price for getting started with VDI using Hyper-V and Windows Server 2008 R2 is compelling -- free -- assuming you already have purchased or are going to purchase the necessary Windows licenses.

VMware View: VMware Inc. is a stalwart in the virtualization industry, but in relative terms is new to the VDI field. Still, VMware View is a good choice when bandwidth is limited and user count is high.

VMware uses a native protocol, PC over IP (PCoIP), but it can also fall back to RDP -- although doing so limits some compression and monitor support features.

PCoIP enables support for some extreme monitor configurations, so View is a good choice for visually demanding users or specialized applications like computer-aided design or employees who work with large spreadsheets.

Again, however, one of the chief complaints about the VMware View platform is price. Getting started costs anywhere from $50 to $250 per concurrent user, not to mention the VMware licenses needed to run the vSphere 4 machines and vCenter management components. Budgeting on the higher end of that spectrum will get you dynamic desktop creation, application packaging and other nice-to-haves.

Sun Virtual Desktop Infrastructure: Sun Microsystems Inc. is most definitely a new player in this space, and its VDI 3.0 is certainly worthy of consideration. VDI 3.0 consists of a virtualization engine that is either VMware's ESX product or the software maker's own xVM VirtualBox hypervisor. The VDI Core handles connection brokering and management duties, and the top layer is the client access logic, which can either be a traditional thin client, an RDP session or a connection through Sun's Secure Web Access portal.

Beware, however, that Sun's VDI is Solaris-centric. If you can't get comfortable on the Solaris platform for your virtualization infrastructure, you should probably look elsewhere. In addition, the future of Sun products is clouded due to its recent acquisition by Oracle.

Overall, while the ROI of a virtual desktop infrastructure isn't as clear up front as server virtualization, it can be a good option for midsized organizations looking to mobilize their workforce and deploy software and updates quickly and efficiently.

Jonathan Hassell is president of The Sun Valley Group Inc. He's an author, consultant and speaker residing in Charlotte, N.C. Hassell's books include RADIUS, Learning Windows Server 2003, Hardening Windows and, most recently, Windows Vista: Beyond the Manual. Contact him at

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