“We can get around 75 users on a dual-CPU, quad-core blade, but the sweet spot is around 60,” claims Shawn Scott, network specialist at Huntsville Hospital in Huntsville, Ala. VirtualIron's Barclay notes that most VDI host servers aren't exactly big iron: “The typical VDI server is a two-way quad-core with iSCSI, which is dirt cheap, and the terminals are $200 thin clients that round out the package.”
The VDI field is wide open at the moment, with dozens of vendors selling fresh solutions. Citrix has released a functional broker package and is working on improving its architecture to fully integrate VDI into its offering. Leostream has released a solution that works with VMware called Hosted Desktop Connection Broker, which functions in much the same way, offering VDI connectivity to selected thin clients (though it borrows third-party hardware to provide SSL support). Dunes’ VD-O offering is similar, whereas Sun’s Sun Ray-based broker and the workSpace product developed by Propero (recently acquired by VMware) offer integrated SSL plus an array of other features.
VMware is in the game, too, with its VDM broker, which shares most of the above features. All of these brokers provide such features as single sign-on and shared pools; some also offer automated pool provisioning and application publishing. These products are still in their infancy, and are definitely VMware-centric, designed to be used in environments specifically built around VMware’s VI3 virtualization framework.
Some of the more advanced brokers come from Provision Networks and 2X. These tools can serve as VDI brokers, but can also extend beyond the virtual realm, offering desktop session connections to VMware clients, VirtualIron clients, Microsoft Virtual Server clients, as well as physical hardware, such as blade systems. Some even have the capability of connecting to Citrix MetaFrame, Microsoft Terminal Services, or TN3270 sessions. In this fashion, they serve as a general clearinghouse for all thin-client computing.
With these tools, it’s possible to create a heterogeneous thin-client computing environment built around whatever technology is the best fit for the user. This is a very attractive proposition for infrastructures with existing thin-client computing installations.
With a global connection broker, it’s possible to build policies that dictate different frameworks for different user sessions. Heavier users that require more robust and responsive sessions can be directed to a session running on a dedicated blade in a blade chassis, while lighter users are directed to a VDI session running under VMware. A specific user class may be already built into a Citrix MetaFrame farm, and thus, those users are connected to a Citrix server for their desktop session. This approach can be an invaluable tool to bring the promise of a complete thin-client infrastructure to reality.