NComputing is the only VDI solution of the three reviewed that provides its own virtualization layer -- no VMware, Citrix, or Microsoft hypervisor required. NComputing's vSpace is a virtualization application with an ultrasmall footprint that runs on any Windows XP or Windows Server 2003 host operating system. Much like Terminal Services, it carves up the underlying system's resources among multiple users, allowing a single computer to host as many as 30 simultaneous desktops. Performance on a LAN was excellent, but the NComputing solution suffered some performance issues over a WAN.
Because vSpace is so low-overhead and well-optimized, it doesn't require the latest in server virtualization technology to handle multiple users. For instance, an off-the-shelf desktop PC with 4GB of RAM and a decent CPU can host up to 30 simultaneous clients on Windows XP Pro. This does not mean that a group of engineers can all run AutoCAD on this host, but normal everyday business apps, like word processing and email, will have little trouble. (See InfoWorld's "Thin Client Computing Deep Dive Report" for more on Terminal Services and thin clients.)
One downside to the NComputing solution, as with Pano Logic, is that it works with the vendor's proprietary access devices only. There is no support for third-party thin clients, software clients on laptops, or Web-based remote access. The L-Series client devices -- I tested the paperweight-sized L300 -- are stand-alone Ethernet-enabled devices that require only a VGA monitor and USB keyboard and mouse. There are no moving parts in the L300 -- no noisy fans or spinning hard drives. The L300 comes with two USB 2.0 ports for remote devices, two USB 2.0 ports for keyboard and mouse, 1/8-inch microphone and speaker jacks, a 10/100Mbps Ethernet port, and a standard DB15 VGA port. It is powered by a 12V DC power brick. Power consumption never exceeded 5W.
NComputing performance and scalability
During my tests, I had 10 L300 endpoints connected to an older Xeon-based Windows Server 2003 host (4GB of RAM) with Microsoft Office 2003, IE 8, and Windows Media Player installed. I had no trouble browsing the Web or doing basic office tasks with all clients connected. Even media playback, from either Windows Media Player or YouTube, was handled with no discernable issues. Server resource statistics on my host system showed that the guest VMs played a minimal role in resource utilization. I feel that NComputing's claim that a server only needs 4GB of RAM to host 30 simultaneous users is probably right on.
An obvious concern is scalability, as many deployments will need to scale beyond a few dozen users. This could be accomplished by combining vSpace with "traditional" virtualization -- that is, running virtualized vSpace servers on a hypervisor such as VMware, Hyper-V, or XenServer. By deploying vSpace in multiple virtual machines and load balancing across multiple servers, you could not only support hundreds of users but also bring fault tolerance to the system. I tested this successfully by turning up a Windows Server 2003 virtual server with vSpace installed on VMware ESX 4.1. My L300 clients connected with ease and didn't treat the virtualized server any differently from the physical one.
Your organization will have to make a philosophical decision with respect to vSpace's OS-based virtualization versus the full virtualization provided by Kaviza and Pano Logic. Because vSpace divides a single operating system among multiple users (versus providing each user with a distinct VM as Kaviza and Pano Logic do), some admins will consider it nothing more than a Terminal Server replacement. Although this is a fair argument, it doesn't do vSpace justice. vSpace handles resource allocation far more efficiently than Terminal Server, and it did a good job of isolating each user session to help prevent one bad session from affecting others.
NComputing virtual desktops
Much like the other VDI solutions, NComputing wouldn't be a good fit for a large office full of AutoCAD or Adobe Premier Pro users. But for small to medium-size offices running mainstream business apps, vSpace can handle most day-to-day production tasks with ease. I had no trouble using Microsoft Office 2003 or any of the big three browsers from inside a vSpace session.
For the administrator, provisioning desktops couldn't be more straightforward. There are no virtual machines to create or templates to manage as in Kaviza and Pano Logic. Just install all of the applications on the host and create your users. Like the other solutions, NComputing uses Active Directory roaming profiles to personalize each user session, configuring the desktop with the user's My Documents folder, Outlook email settings, printer assignments, desktop icons, and other personal settings at logon. Unlike Kaviza and Pano Logic, NComputing doesn't support persistent, personalized desktops. If one user installs a new application, then that application will be available to all users on the same host.
Management chores are handled by the vSpace Console. This Windows-based utility is a mix of vSpace configuration settings and a sort of pseudo Group Policy engine for users' desktops. Using vSpace Console, I was able to set specific user, software, and local computer policies such as logon/logoff scripts, network settings, and printer handling. For instance, I created a policy that prevented access to the command prompt, denied access to other critical Windows options (such as Control Panel), and removed the My Computer icon from the desktop. Admins can define these and other policies using Windows' Group Policy engine, but vSpace makes it much easier to implement them for vSpace users. The vSpace Console also allowed me to view and manage connected user sessions, going so far as to let me shadow a live session.
NComputing vSpace and the L300 endpoints may be the easiest of the three turnkey VDI solutions to install and maintain; there is almost no learning curve to deploying the solution. The L300 client is not only small and power efficient, but the fact that there are no moving parts means no noise and greater reliability. I don't like being locked into one specific endpoint, but for small or initial VDI deployments and moderate workloads, the NComputing solution works well.