Client virtualization Middleton WI

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Reasons for client virtualization

The primary reason organizations are interested in pursuing client virtualization solutions has to do with the challenges they face in managing large numbers of computers controlled by end users. Although machines located in data centers typically have strict procedures about what software is loaded on them and when they’re updated with new software releases, end user machines are a whole different story.

Because loading software is as easy as sticking a disc into the machine’s CD drive (or a thumb drive into a USB slot), client machines can have endless amounts of non-IT-approved software installed. Each application can potentially cause problems with the machine’s operating system as well as other approved applications. Beyond that, other nefarious software can get onto client machines in endless ways: via e-mail viruses, accidental spyware downloads, and so on. And, the hard truth is that Microsoft Windows, the dominant client operating system, is notorious for attracting attacks in the form of malware applications.

Added to the end user–caused problems are the problems inherent to client machines in general: keeping approved software applications up to date, ensuring the latest operating system patches are installed, and getting recent virus definitions downloaded to the machine’s antivirus software.

Mixed together, this stew is a miserable recipe for IT. Anything that makes the management of client machines easier and more secure is of definite interest to IT. Client virtualization offers the potential to accomplish this.

Three main types — or flavors, if you will — of client virtualization exist: application packaging, application streaming, and hardware emulation.

Application packaging

Although the specifics of how application packaging is accomplished vary from one vendor to another, all the methods share a common approach: isolating an application that runs on a client machine from the underlying operating system. By isolating the application from the operating system, the application is unable to modify underlying critical operating system resources, making it much less likely that the OS will end up compromised by malware or viruses.

You can accomplish this application-packaging approach by executing the application on top of a software product that gives each application its own virtual set of system resources — stuff like files and registry entries. Another way to accomplish application packaging is by bundling the application and the virtualization software into a single executable program that is downloaded or installed; when the executable program is run, the application and the virtualization software cooperate and run in an isolated (or sandboxed) fashion, thereby separating the application from the underlying operating system.

Application packaging is a great way to isolate programs from one another and reduce virus transmission, but it doesn’t solve the problem of end users installing non-packaged software on client machines.

One thing to keep in mind with this approach is that it causes additional work as the IT folks prepare the application packages that are needed and then distribute them to client machines. And, of course, this approach does nothing to solve the problem of end users installing other software on the machine that bypasses the application packaging approach altogether. If you’re loading a game onto your business laptop, you’re hardly likely to go to IT and request that someone create a new application package so that you can run your game securely, are you?

Products that provide application packaging include SVS from Altiris, Thinstall’s Virtualization Suite, and Microsoft’s SoftGrid.

Application streaming

Application streaming solves the problem of how to keep client machines loaded with up-to-date software in a completely different fashion than application packaging. Because it’s so difficult to keep the proper versions of applications installed on client machines, this approach avoids installing them altogether. Instead, it stores the proper versions of applications on servers in the data center, and when an end user wants to use a particular application, it’s downloaded on the fly to the end user’s machine, whereupon he or she uses it as though it were natively installed on the machine.

This approach to client virtualization can reduce the amount of IT work necessary to keep machines updated. Furthermore, it happens transparently to the end user because the updated application is automatically delivered to the end user, without any physical software installation on the client. It also has the virtue of possibly allowing client machines less capability to be deployed because less disk space is required to permanently store applications on the client hard drive. Furthermore, if this approach is taken to its logical conclusion and the client machine has no hard drive, it is possible that less memory is required because only the official IT applications can be executed on the machine. This result is because the end user can’t execute any programs other than the ones available from the central server.

Although at first glance, this approach might seem like a useful form of virtualization, it is really appropriate only in certain circumstances — primarily situations in which end users have constant connectivity to enable application downloads when required. Examples of these situations include call centers and office environments where workers rarely leave the premises to perform work duties. In today’s increasingly mobile workforce world, these circumstances apply to a small percentage of the total workforce. Perhaps the best way to think about this form of virtualization is as one that can be very useful in a restricted number of work environments.

This type of virtualization is offered by AppStream’s Virtual Image Distribution, Softricity’s Softgrid for Desktops, and Citrix’s Presentation Server. Softricity has recently been acquired by Microsoft, and its SoftGrid product will soon be available as part of the Windows Server platform. SoftGrid will offer the capability of streaming applications to remote desktops.

Application streaming is best suited for static work environments where people don’t move around much, such as call centers and form-processing centers, although some organizations are exploring using it for remote employees who have consistent network connectivity to ensure that applications can be streamed as necessary.

Hardware emulation

Hardware emulation is a very well-established form of virtualization in which the virtualization software presents a software representation of the underlying hardware that an operating system would typically interact with. This is a very common type of virtualization used in data centers as part of a strategy to get higher utilization from the expensive servers that reside in them.

Because of the spread of commodity hardware (that’s to say, hardware based on Intel’s x86 chip architecture; these chips power everything from basic desktop machines to huge servers), the same hardware emulation type of virtualization that can be used in data centers can also be used on client machines. (The term commodity refers to the fact that the huge volumes of x86 processors sold make them so ubiquitous and inexpensive that they’re almost like any other mass-produced, unspecialized product — almost as common as the canned goods you can get in any grocery store.)

In this form of client virtualization, the virtualization software is loaded onto a client machine that has a base operating system already loaded — typically Windows, but client hardware emulation virtualization is also available for systems running Mac and Linux operating systems.

After the hardware emulation software is loaded onto the machine, it’s ready to support guest operating systems. Guest OSes are installed via the virtualization software; that is, rather than just sticking a CD into the machine’s drive and rebooting it to install the operating system directly onto the hardware, you use the virtualization software’s control panel to indicate your desire to install a guest OS (which can be either Windows or Linux). It sets up the container (often called the virtual machine, or VM for short) for the guest operating system and then directs you to put the CD in the drive, whereupon the normal installation procedure occurs.

After the installation completes, you control the virtual machine (which is a normal Windows or Linux system) through the virtualization software’s control panel. You can start, stop, suspend, and destroy a VM from the control panel.

Interacting with the VM guest OS is just like interacting with it if it were the only OS on the machine. A guest OS displays graphics on the screen, the VM responds to keyboard and mouse commands, and so on. That’s why it’s called virtualization!

Products offering this type of virtualization are VMware’s VMware Server and Microsoft’s Virtual Server. On the Macintosh, SWsoft’s Parallels product provides hardware emulation virtualization.