IT-driven virtual desktop infrastructure (VDI) initiatives are often motivated by a desire to improve operational efficiency and security while decreasing desk-top capital, maintenance, and management costs. VDI initiatives, however, are at risk of being rejected by desktop users, who are the IT department’s customers, if IT fails to integrate them into acceptance testing and ongoing determination of acceptable performance and availability.
IT professionals involved in VDI initiatives may be tempted to extrapolate from average storage capacity, average CPU, average memory, and average I/O requirements of desktop users to determine the necessary VDI infrastructure. Acceptable performance at the time of need, which is anytime the user wants it, however, is a major determining factor in whether a user will be satisfied with VDI.
Storage infrastructure plays a key role in performance. Storage capacity requirements are relatively predictable and constantly increasing, tempting IT to manage requirements out of one, centralized, homogeneous storage pool. Unlike capacity requirements, however, I/O requirements fluctuate dramatically, both up and down, based upon user activity. Peak I/O requirements are a crucial factor in the user experience, especially during periods of high user activity, such as log-on and log-off times. In order to deliver acceptable performance, VDI managers must pay as much attention to I/O performance of the systems as they do to capacity requirements.
VDI bears little resemblance to a server virtualization project. Even in a world of corporate standards, desk-top users have demanded and often receive a highly-customized experience, so a one-size-fits-all strategy will not work. Some users will compare the VDI implementation to their own beefy desktops, with rich graphics that have been finely tuned, optimizing performance for a specific workload. In addition, each user tends to customize the user interface to fit their style of work, so implementations need to enable and protect the customization of the user interface.
End-user acceptance testing is a critical part of the VDI implementation plan. IT cannot be responsible for acceptance testing and ongoing management of the end-user experience. If end-users perceived performance and usability as sub-par, IT will be dragged into months of escalation meetings and damage control. It will be difficult to control dissatisfied users of VDI, who will either demand a return to the desktop, or, if stymied, find below-the-radar methods of meeting their needs.
Action Item: VDI project managers should analyze workloads and divide desktop users into performance classes, selecting representatives from each class to perform user-acceptance testing of VDI implementations. Users, not IT, should determine acceptable performance. Further, once implemented, maintenance of VDI performance should also be a user-directed initiative. In doing the workload analysis, IT should also recognize at the outset that some users may not fit well within any performance class and may best be left outside of the VDI implementation.