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Windows 7's XP Mode is one example of how virtualization is becoming more useful to home users and business users alike.
Virtualization is a way of getting more out of the same hardware -- are you taking advantage of it

While virtualization is not without its share of detractions, its allure is great. After all, it promises to make compatibility and resource management woes -- two eternal computer problems -- things of the past. 

Imagine being freed from fears of software compatibility, and being able to reclaim your idle hardware for a purpose.  That's the premise behind virtualization.  While new users may still not have heard of virtualization or understand its benefits, the movement is growing and it may eventually become as ubiquitous a concept as the desktop operating system.

Virtualization is divided into two key categories -- application virtualization and platform virtualization.  The goal of application virtualization is to provide compatibility layers.  This could allow you to, say run an old Windows 3.1 program on a Linux operating system.  The open source project Wine is an example of this kind of virtualization.

The second category is platform virtualization -- bringing the whole OS onboard.  There's a variety of ways of accomplishing this with solutions available in both the desktop and server markets.  Some solutions have multiple kernels (a central component of the OS) running in parallel, with one for each virtual machine (full virtualization), while other schemes involve a single kernel managing multiple virtual servers (a server is the interface users use to interact with the OS -- how we perceive Windows) allowing them to all to run at once.  Windows 7's XP Mode is one example of such a scheme -- in Windows 7 a guest virtual machine for Windows XP runs on the system, which communicates through the host Windows 7 kernel.

Some platform virtualization implementations, such as XP Mode, use redirection of input to accomplish application virtualization via platform virtualization rather than a compatibility layer.  The experience is more seamless as the Windows are displayed inline without the need to physically switch to a virtual machine window and navigate through its own windows.

A final important aspect of virtualization is the cloud computing movement.  Though not all cloud computing involves virtualization, many cloud deployments involve sharing virtualized resources over a network.  Shared resources are nothing new, but by virtualizing them, it lowers overhead and ensures that resources are efficiently used.  Google, IBM, and Microsoft are just a few of the major names delving into this field.  An example of cloud computing that even novice users can appreciate is Microsoft Office 2010, which will be available as free web applications for home users.

Virtualization is a fast evolving field and it is not without its problems and obstacles.  One obstacle is cost.  While costs of virtualization are dropping (Windows virtual machines for home users come with copies of Windows 7 Professional at no extra cost), deploying such a solution at your business may require some up-front IT investment and hours.  In the long run it will save costs, but for cash-strapped businesses, this can be a deterrent to adoption, albeit one that will eventually be overcome.

Another more serious challenge is the increased likelihood of interruption of service.  By putting more services on a single set of hardware you raise the damage that could be caused by a power failure -- either at your location or from your system's power supply.  Furthermore, by running your hardware under larger workloads, you run the risk of a higher incidence of part failures.  Again, this is unproven territory as the field is still young, but logic dictates that hardware flexed to its full capacity will likely experience more failures than hardware that spends a significant amount of time in idle.  As the deployment of virtual machines is in the hands of system administrators, it’s up to them to make sure that they're not overburdening hardware.

A final challenge is security.  By placing multiple virtual machines on a single set of hardware, you run the risk of an escalated intrusion threat if an attacker can compromise the hypervisor layer -- the layer beneath the virtual machines.  Also in a guest/host setup (like Windows XP Mode) you run the risk of guest-to-host attacks, which can exploit vulnerabilities in legacy operating systems or applications.  Thankfully, such attacks have thus far been rare, but proof-of-concept exploits show the need for vigilance.  As always, diligent patching and careful system administration can protect your virtualized network against most threats.

With that said, how is virtualization impacting you?   How are you adopting virtualization at your home or business?  And, if you're not adopting virtualization, what's holding you back?

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Lets clarify some things
By JonathanC3 on 7/23/2009 7:59:06 PM , Rating: 2
Before writing an article and list "obstacles" you should learn more about it and test it! I've been working with virtualization for a long time and I am specialized in virtualization. So lets address a few points:

- Application virtualization, desktop virtualization and server vitualization are different and involve different technologies and process. Proprely implemented and configured it works very well and it will be secure. Some application virtualization technologies allow you to deploy older apps on new OS/hardware without issues.

- Having multiple virtual machines/server (VM) on a physical system can become a single point of failure but there are solutions. When virtualizing production servers, you should have your VM hosted on a SAN, NAS or DAS and use fiber obtic or iSCSI. It is also recommended to implement technologies such as Live Motion(Microsoft Hyper-V R2) or V-Motion(VMware). With those, you can move VM's for one physical box to an other without service interuption! You can(and should when possible) also implement clustering and failover at the host and at the VM level. With all this, even if one physical server goes down, it should have little or no impact.
* Keep in mind that you are not supposed to and should no load your physical server to it's limit.

- You say virtualization is expensive. Well if you don't plan on bying new servers or if your needs don't grow it will. However, if you plan on bying new Windows Server machine(most common) you should think about virtualization. Here's an example with Hyper-V from Microsoft which I prefer: if you by a new machine with Windows Server 2008 Enterprise, not only do you get your main box, but the license can also be used for 4 addtional VM with the same OS for FREE.(You have to pay for each license on VMware) So, the cost might be slightly higher because you're going to put more RAM in that physical system but the ROI is better.

- About performance, this is mostly a question of proper configuration and use. I've virtualized produciton environments and so far there are no big differences. Most enterprise applications work fine in VM and if you do your job well, you will put heavy I/O apps(i.e:SQL, Exchange) on physical/passtrough disk, not virtual disks! This is one very important thing to keep in mind.

- Management is now centralized using Microsoft Virtual Machine Manager(which can also manage VMware VM's)or WMware vCenter. This also makes VM provisioning very simple and fast.Using Microsoft SCVMM, you can even do live physical to virtual migration and convert VMware to Hyper-V.

Jonathan C
MCP, MCTS - Windows Server Virtualization

RE: Lets clarify some things
By pupdawg21 on 8/20/2009 9:59:16 AM , Rating: 2
All good things. Except the one issue you mention where you get 4 VMs free with Windows Server 2008 Enterprise as the Virtulization platform and you don't with VMWARE. If you deploy a Windows Server Enterprise license on VMWare the 4 free VM's still apply. The difference would be that you would have the added expense of the VMWare platform itself where as with Windows Server 2008 Enterprise with Hyper-V the virtualization platform cost is already paid for.

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