Desktop virtualization

Desktop virtualization (or Virtual Desktop Infrastructure) is a server-centric computing model that borrows from the traditional thin-client model but is designed to give system administrators and end-users the best of both worlds: the ability to host and centrally manage desktop virtual machines in the data center while giving end users a full PC desktop experience.

The user experience is intended to be identical to that of a standard PC, but from a thin client device or similar, from the same office or remotely.

Many commercial solutions also add the ability to switch some incoming client sessions (using connection broker software) towards traditional shared desktop systems such as Microsoft's Terminal Services or Citrix's application servers, blade servers or even to individual unused physical desktop computers.

Rationale

Installing and maintaining separate PC workstations is complex, and traditionally users have almost unlimited ability to install or remove software. Corporate information technology departments, and users have therefore often used Terminal Services or Citrix's Presentation Server to provide a stable, "locked down" desktop environment out to the user, who could be either using a regular desktop PC, or a small, quiet and robust thin client.

Desktop virtualization provides many of the advantages, but gives users much more flexibility. Each can install and configure their own applications. Users also gain the ability to access their normal desktop from other locations.

Advantages

• Instant provisioning of new desktops
• Near-zero downtime in the event of hardware failures
• Significant reduction in the cost of new application deployment
• Robust desktop image management capabilities
• Normal 2-3 year PC refresh cycle extended to 5–6 years or more
• Existing desktop-like performance including multiple monitors, bi-directional audio/video, streaming video, USB support etc.
• Ability to access the users' enterprise desktop environment from any PC, (including the employee's home PC)
• Desktop computing power on demand
• Multiple desktops on demand
• Self provisioning of desktops (controlled by policies)
• Zero downtime in the event of client failure

Desktop virtualization industry outlook

The worldwide hosted virtual desktop (HVD) market will accelerate through 2013 to reach 49 million units, up from more than 500,000 units in 2009, according to Gartner Inc. Worldwide HVD revenue will grow from about $1.3 billion to $1.5 billion in 2009, which is less than 1 percent of the worldwide professional PC market, to $65.7 billion in 2013, which will be equal to more than 40 percent of the worldwide professional PC market.

The Gartner report, "Emerging Technology Analysis: Hosted Virtual Desktops, also stated while PC hardware expenditures would fall, enterprises would require more servers, network bandwidth and software to support new architectures.

Gartner estimated that approximately 15 percent of current worldwide traditional professional desktop PCs would migrate to HVDs by 2014, equal to about 66 million connected devices. The U.S. would reach double that of the worldwide average with over 18 million connected devices. After an initial slow start, the HVD market would rally in 2010 and 2011.

"Despite the further improvements in performance and manageability that are expected of HVDs in 2009, the current economic downturn is expected to inhibit the adoption of HVDs in the short term because HVD deployments require large upfront investments in server and network infrastructure," Jump said. "Because of IT budget cuts, we expect many planned HVD implementations to be delayed from 2009 into 2010 and 2011."

Desktop virtualization licensing

With desktop virtualization estimated at present on more than half of the worlds computers, Microsoft have enforced a license to allow users to view desktops in a virtual environment. VECD or Virtualized Enterprise Centralised Desktop license enables users to view client Microsoft Windows operating systems in a virtual environment. The license stipulates that every end point device connecting to a virtual desktop must have a VECD license. Microsoft have recently reduced the annual VECD cost to $23 per fat client and $110 per thin client.

The licensing has certain requirements which must be met in order to qualify for VECD. The most notable being that each company who registers for VECD must have both Volume Licensing and Software Assurance with Microsoft. With these pre-requisites in place, companies can signup for VECD and implement in one of two ways:

• Implement VDI internally. Many larger organisations are training staff in the key VDI products and implementing virtualization throughout their organisation. Although there is an associated setup cost, this option tends to give companies the flexibility to build their virtual infrastructure from the ground up.

• Outsource VDI. Other organisations are outsourcing their VDI to third party ISP/V's. This removes the initial cost to setup VDI but still requires assessment of the individual business and ongoing support and maintenance. In terms of VDI, the client who has the Volume Licensing and Software Assurance must purchase the VECD licenses themselves, moreover the physical servers in the datacentre hosted by the service provider must only contain the clients of whom the VECD licensing belongs and no other clients can be located on that same physical server.

Many smaller companies who do not have Volume Licensing or Software Assurance and would like to implement VDI are considering Volume Licensing. Outside of this bracket certain virtualization technologies allow you to publish server Microsoft Windows operating systems and split the processes between individual users. Programs such as Microsoft Terminal Services allow users to logon to server operating systems and run applications much as they would using traditional VDI, only that any one company would have their own virtual machine rather than individual users. This option seems fairly common place in the ISP/V space as end users do not require VECD but can still offer virtual hosted desktops.

The key point to remember is that streaming a client OS without VECD is violating Microsoft licensing terms, but streaming a server OS is allowed as long as the relevant Windows and Terminal Services licenses are present. For ISV's this type of agreement is usually implemented on a SPLA agreement allowing the vendor to pay per maximum concurrent user per month for each license required.

It seems quite clear that desktop virtualization cannot be ignored, Brian Gammage, Gartner's head VP on virtualization stated last week that "soon virtualization won't be the buzz word on everyone's lips, just as people now don't talk about the BIOS on their computer. Soon virtualization will be built into everything we do without us even knowing it".

Notable providers

• Ericom's WebConnect
• Citrix's XenDesktop
• Kaviza's VDI-in-a-box (http://www.kaviza.com)
• HOB GmbH & Co KG HOB VDI Business
• Parallels Desktop for Mac
• Parallels VDI
• VMware Fusion
• VMware VDI