Flavors of Desktop Virtualization By Barb Goldworm published: Wednesday, November 14 2007
Last month I talked about the changes happening in the server virtualization space as it moves to a multi-horse race - complete with competition and new and improving technologies from three major industry players – VMware, Citrix and Microsoft. This month I want to talk about how leveraging technology from these and other vendors can extend the benefits of virtualization out to the desktop.
As IT shops have gained experience with server virtualization and completed at least the initial phases of consolidation projects, those on the leading edge have started thinking about how else they can benefit from their virtualization software, tools, expertise and experiences. In going beyond consolidation into what some call Virtualization 2.0, two areas commonly emerge next– leveraging virtualization to improve availability/disaster recovery, and extending virtualization out to the desktop and ultimately to the application level. We’ll cover availability and DR another time and focus here on desktop virtualization.
In addition to the penetration of server virtualization, another factor that has raised interest in desktop virtualization has been the emergence of IT shops evaluating Vista and reviewing the hardware upgrade requirements for its implementation across their entire desktop user base. Before making that level of investment, many shops are re-evaluating their overall corporate desktop strategy and considering alternatives. This strategic evaluation involves examining your users’ requirements - for all of the different types of users and use cases across your organization. Profiling your users and truly understanding what different types of users do and what they will need in the future is critical as you evaluate the various options that virtualization and other new options like PC/workstation blades can offer.
To start looking at desktop virtualization, it is important to discuss various terms that are often used and confused.
Virtual desktops, virtual clients, hosted desktops, or centralized desktops
These terms are often used interchangeably to mean the use of a server virtualization back-end infrastructure to allow a user to connect from a PC browser or thin client through some type of connection broker software to a virtual machine running on a virtual server. With virtual clients, you eliminate the underutilized physical PCs sitting idle under people’s desks while they’re off in meetings or gone home – and replace them with virtual machines, taking up little to no resources when not active.
VMware has done a fair amount of evangelizing this approach, with their Virtual Desktop Infrastructure or VDI. There are a number of large VMware VI3 shops who have implemented VDI, but mostly still in small pilot projects (though there are starting to be some fairly large implementations emerging). Prior to their IPO, VMware acquired a company called Propero who had developed one of the early connection brokers. VMware has just released their first VMware version of this product as Virtual Desktop Manager or VDM. VDM initially brokers only to XP or Vista VMs running on a VMware back-end, and is certified with only a few thin clients that support embedded XP, but VMware describes VDM as the beginning platform for additional desktop management capabilities going forward.
Citrix announced their version of a virtual client solution as their Dynamic Desktop Initiative or DDI, prior to their acquisition of XenSource, with their initial connection broker called Desktop Broker. Initially tied into their Citrix Presentation Server, Desktop Broker evolved into Desktop Server, offering integrated connection brokering to either Presentation Server or a VM, generally hosted on a VMware back-end infrastructure. Post XenSource acquisition, this product has now evolved into XenDesktop, bundling in XenServer, raising questions about future support for non Xen hypervisors. The interesting potential here is a blurring of the lines and merging of management, spanning users connecting to Presentation Server and/or to VMs.
Connection broker software is also available from other smaller players like Leostream, who has been a primary component in IBM’s virtual client strategy, as well as a part of their new workstation blade offering. Leostream’s connection broker can connect users to back-end workstation blades, VMs, or Citrix Presentation Server and offers some nice additional features like global roaming. Provision Networks also offers connection broker software, along with their extended RDP protocol and product suite which competes with Citrix (and their ICA protocol) aiming to improve the user experience for remote and thin client users. Provision Networks was acquired this month by Quest Software, so it will be interesting to see how much Quest’s size and resources will help grow awareness and market growth of Provision’s Virtual Access Suite.
Client hosted PCs or Virtual PCs, also sometimes called virtual desktops
A different type of desktop virtualization involves a virtualization layer running on an individual desktop as opposed to a server. This approach targets a very different use case. By running virtualization on the desktop/PC, a user can run multiple guest VMs (either running the same or different operating systems) on their own desktop. This was actually the first type of x86 virtualization offering back around 2001, in what became VMware Workstation and VMware Player. Virtual PC from Connectix was another early example of this approach - subsequently acquired by Microsoft. These products are great for development and testing, since a developer can run a guest VM on their desktop and test in a completely isolated environment, without requiring any additional hardware. VMware Fusion and SWsoft Parallels offer similar capabilities but adding emulation capability, allowing Mac users to run Windows and/or Linux virtual machine sessions.
Another variation on this approach is in managed virtual PCs. VMware’s ACE offering uses the Player capability in the VMware product line, but adds central management through an administrative console which can create locked-down VMs. ACE allows for centralized creation and management of a VM, which can then be run on any workstation via the Player technology, but runs that VM as an isolated and controlled environment. (For example, a company can allow a contractor to take a Pocket ACE VM on a USB stick that can run on the contractor’s laptop and can connect to the employer’s network, but cannot interact with anything else on that laptop, including the local hard drive.) Moka5 also has an offering based on this concept.
Presentation Virtualization or server-based computing
Server-based computing (which has been around longer than x86 virtualization) offers the ability to run shared, multi-user applications on a terminal server, with users connecting to those applications from a thin client (or fat client from a browser) which run the user interface. Since this approach separates the user interface (or presentation) from the execution of the application, the term presentation virtualization is now being used by folks like Microsoft and Citrix, to compare and contrast it with other types of virtualization. The terminal server can be either Microsoft Windows Terminal Services or Citrix Presentation Server (which actually builds on and includes a license for Terminal Services). Citrix Presentation Server offers more management features and greater flexibility, and is generally the platform of choice for larger organizations. Terminal Services in Windows Server 2008 has improved with some additional features, but still doesn’t have the breadth and scalable management features of Presentation Server.
Conclusions
All of these types of virtualization bring benefits which can address different types of users within your organization. In addition, application virtualization and streaming (used separately or in conjunction with these technologies) brings additional benefits in addressing the past headaches of managing distributed desktop software (topic for a future column). Of course, there will always be some users who require their own physical workstation (whether it resides under their desk or in a workstation/PC blade chassis back in a closet or in the datacenter). Understanding your users and their requirements and matching each type to the best technical solution involves listening, learning and planning, like everything else in IT.
Biography
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Barb Goldworm is president and chief analyst of Focus Consulting, a market research, analyst and consulting firm focused on systems, software and storage. Barb has spent 30 years in various senior management, marketing, sales, engineering, technical and industry analyst roles with IBM, StorageTek, Novell, Enterprise Management Associates and several successful startup ventures. Barb began working with virtualization at IBM in the late 1970s (as a VM technical specialist), and later was VP of Marketing for the company that developed the first PC software distribution product in the mid-1980s (acquired by Novell in 1992). In 2006, she was commissioned by Wiley Publishing to write a book on blades - she agreed but changed the focus of the book to include a major emphasis on virtualization - the book was released in 2007, entitled "Blade Servers and Virtualization: Transforming Enterprise Computing While Cutting Costs", available on Amazon.com, Borders and Barnes and Noble.
Barb is a frequent keynote speaker, chair, and presenter at industry events. In 2007, she chaired the Server Blade Summit on Blades and Virtualization, and has been the keynote speaker for numerous Virtualization Summits this year. She also created and chaired the Interop Network Storage Track and has been one of the top 3 ranked analyst/ knowledge expert speakers at SNW.
Barb has published extensively since the 1990s, and has been a regular contributor to Network World, Computerworld, Computerworld Storage Networking World Online, Tech Target, and now Virtual Strategy Magazine. She has authored numerous research studies, landscape reports, and business and technical white papers on systems, software, storage, storage networking and enterprise management. Barb can be reached at
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