Virtual desktop infrastructure (VDI) has faced plenty of challenges: complexity, high cost, heavy server and storage requirements, and end-user dissatisfaction, to list the common complaints. But VDI has also delivered plenty of innovation and experimentation, with vendors taking a variety of approaches to lower the hurdles to implementation, ease the management burden, and address a fuller range of user needs.
One subset of VDI, dubbed client-hosted or offline mode, is an interesting hybrid that takes advantage of local hardware resources -- the PCs and laptops already in users' hands -- while still fulfilling the promise of easier, central management. Naturally, the server and storage requirements for managing desktop images pale considerably to those for hosting all of the desktop computing power in the data center. With offline VDI, there's no need for high-end multiprocessor servers with loads of RAM, and concerns about WAN usage and network latency disappear. Instead of "wasting" local resources on a PC or laptop when remoting into a hosted VDI solution, those resources are put to good use.
[ Download InfoWorld's Virtual Desktop Infrastructure Deep Dive special report | InfoWorld review: Desktop virtualization made easy | VDI shoot-out: Citrix XenDesktop 5.5 vs. VMware View 5 | Keep up on news in virtualization by signing up for InfoWorld's Virtualization newsletter. ]
The difference between offline VDI and a traditionally installed desktop, of course, is virtualization. The desktop OS runs on the local hardware in a virtual machine, abstracted from the underlying hardware via a hypervisor. Because the hypervisor runs the show, an endpoint can run multiple instances of different operating systems and keep them completely isolated from one another. IT maintains control over the VM running on the endpoint by way of centrally stored golden images and endpoint policy enforcement.