For Virtual Desktops, Latency Matters

Up until now, pilot server virtualization projects have been the domain of Fortune Global 500 enterprises. This year, Gartner anticipates a sea change in VM deployment that will bring a higher penetration of deployed VMs to SMEs than the fabled Global 500. In particular, Gartner estimates 50 percent of the server workloads on Intel architecture will be running on VMs by the end of 2012. In terms of raw numbers, that will put the number of deployed X86 server VMs at 58 million by the end of 2012.

Nonetheless, IT may well find that the distributed computing sea change in server virtualization will be dwarfed by a rapidly growing tsunami in virtualized desktops. On the client side, the corporate pool of desktop and laptop PCs has long been the mare incognitum of IT resources. The sheer number of client devices makes the over provisioning of CPU and storage resources for these systems a huge capital expense. The provisioning of business PCs, however, is only the tip of the iceberg. On the business side of the ledger, the impediment to advancing distributed computing lies in the amorphous distribution of client computing devices, which escalates management costs and ensures that IT’s ability to optimize resource utilization will be rudimentary at best.

What stymied previous IT attempts to optimize this resource is the strength of the characteristic that made the PC an inextricable thread in the business fabric: the power of the personal experience. While end user may not care where bits are manipulated, they care very much about how they interact with the process. For end users, PCs accessing terminal services are just fancy terminals. That’s why Virtual Desktop Infrastructure (VDI), which virtualizes the entire personal experience, presents IT with a serious opportunity to harness and optimize the resources associated with client PCs.

In terms of today’s $150 billion worldwide market in business PCs, Gartner pegs client systems deployed on VMs to be around 500,000—about the level of a rounding error. Nonetheless, as IT finds it conceptually easy to leverage existing infrastructure to offset VDI entry costs, Gartner projects the percent of new business PCs being deployed on VMs to rapidly rise to 40%. According to Gartner, IT in the US will lead this trend by migrating 30 percent of their installed base of desktop PCs to VMs by 2014. At that rate, the ranks of VMs running client systems will swell to over 18 million.

Density Dynamics

While it’s easy to conceptualize extending a server-centric virtual operating environment (VOE) to a VDI, there are a number of profound differences that can stymie the process. In particular, best practices call for deploying desktop VMs four to eight times more densely than server VMs. What makes dense deployment plausible is the sporadic nature of desktop PC usage. While dense VM deployment enhances the potential for significant cost savings, dense deployment also increases the need for IT to be prepared for resource-utilization storms involving I/O, memory, and CPU resources.

The pivotal resource to make this transformation in distributed computing possible is a SAN-based storage infrastructure that scales out in capacity and performance. What makes storage so important are the inextricable links to the capital and operational expenses that IT must restructure to maximize the return on investment (ROI) of a VDI initiative. What makes storage so difficult is the need for IT to ensure that sufficient SAN bandwidth is available to meet service metrics in a highly variable environment.