SMB IT Journal

Virtualization as an enterprise concept is almost as old as business computing is itself.  The value of abstracting computing from the bare hardware was recognized very early on and almost as soon as computers had the power to manage the abstraction process, work began in implementing virtualization much as we know it today.

The earliest commonly accepted work on virtualization began in 1964 with the IBM CP-40 operating system developers for the IBM System/360 mainframe.  This was the first real foray into commercial virtualization and the code and design from this early virtualization platform has descended today into the IBM VM platform that has been used continuously since 1972 as a virtualization layer for the IBM mainframe families over the decades.  Since IBM first introduced virtualization we have seen enterprise systems adopting this pattern of hardware abstraction almost universally.  Many large scale computing systems, minicomputers and mainframes, moved to virtualization during the 1970s with the bulk of all remaining enterprise systems doing so, as the power and technology were available to them, during the 1980s and 1990s.

The only notable holdout to virtualization for enterprise computing was the Intel IA32 (aka x86) platform which lacked the advanced hardware resources necessary to implement effective virtualization until the advent of the extended AMD64 64-bit platform and even then only with specific new technology.  Once this was introduced the same high performance, highly secure virtualization was available across the board on all major platforms for business computing.

Because low cost x86 platforms lacked meaningful virtualization (outside of generally low performance software virtualization and niche high performance paravirtualization platforms) until the mid-2000s this left virtualization almost completely off of the table for the vast majority of small and medium businesses.  This has lead many dedicated to the SMB space to be unaware that virtualization is a well established, mature technology set that long ago established itself as the de facto pattern for business server computing.  The use of hardware abstraction is nearly ubiquitous in enterprise computing with many of the largest, most stable platforms having no option, at least no officially support option, for running systems “bare metal.”

There are specific niches where the need to avoid hardware abstraction through virtualization is not advised but these are extremely rare, especially in the SMB market.  Typical systems needing to not be virtualized include latency sensitive systems (such as low latency trading platforms) and multi-server combined workloads such as HPC compute clusters where the primary goal is performance above stability and utility.  Neither of these are common to the SMB.

Virtualization offers many advantages.  Often, in the SMB where virtualization is less expected, it is assumed that virtualization’s goal is consolidation where massive scale cost savings can occur or in providing new ways to provide for high availability.  Both of these are great options that can help specific organizations and situations but neither is the underlying justification for virtualization.  We can consolidate and achieve HA through other means, if necessary.  Virtualization simply provides us with a great array of options in those specific areas.

Many of the uses of virtualization are artifacts of the ecosystem such as a potential reduction in licensing costs.  These types of advantages are not intrinsic advantages to virtualization but do exist and cannot be overlooked in a real world evaluation.  Not all benefits apply to all hypervisors or virtualization platforms but nearly all apply across the board.  Hardware abstraction is a concept, not an implementation, so how it is leveraged will vary.  Conceptually, abstracting away hardware whether at the storage layer, at the computing layer, etc. is very important as it eases management, improves reliability and speeds development.

Here are some of the benefits from virtualization.  It is important to note that outside of specific things such as consolidation and high availability nearly all of these benefits apply not only to virtualizing on a single hardware node but for a single workload on that node.

1. Reduced human effort and impact associated with hardware changes, breaks, modifications, expansion, etc.
2. Storage encapsulation for simplified backup / restore process, even with disparate hardware targets
3. Snapshotting of entire system for change management protection
4. Ease of archiving upon retirement or decommission
5. Better monitoring capabilities, adding out of band management even on hardware platforms that don’t offer this natively
6. Hardware agnosticism provides for no vendor lock-in as the operating systems believe the hypervisor is the hardware rather than the hardware itself
7. Easy workload segmentation
8. Easy consolidation while maintaining workload segmentation
9. Greatly improved resource utilization
10. Hardware abstraction creates a significantly realized opportunity for improved system performance and stability while lowering the demands on the operating system and driver writers for client operating systems
11. Simplified deployment of new and varied workloads
12. Simple transition from single platform to multi-platform hosting environments which then allow for the addition of options such as cloud deployments or high availability platform systems
13. Redeployment of workloads to allow for easy physical scaling

In today’s computing environments, server-side workloads should be universally virtualized for these reasons.  The benefits of virtualization are extreme while the downsides are few and trivial.  The two common scenarios where virtualization still needs to be avoided are in situations where there is specialty hardware that must be used directly on the server (this has become very rare today, but does still exist from time to time) and extremely low latency systems where sub-millisecond latencies are critical.  The second of these is common only in extremely niche business situations such as low latency investment trading systems.  Systems with these requirements will also have incredible networking and geolocational requirements such as low-latency Infiniband with fiber to the trading floor of less than five miles.

Some people will point out that high performance computing clusters do not use virtualization, but this is a grey area as any form of clustering is, in fact, a form of virtualization.  It is simply that this is a “super-system” level of virtualization instead of being strictly at the system level.

It is safe to assume that any scenario in which you might find yourself in which you should not use virtualization you will know it beyond a shadow of a doubt and will be able to empirically demonstrate why virtualization is either physically or practically impossible.  For all other cases, virtualize.  Virtualize if you have only one physical server and one physically workload and just one user.  Virtualize if you are a Fortune 100 with the most demanding workloads.  And virtualize if you are anyone in between.  Size is not a factor in virtualization; we virtualize out of a desire to have a more effective and stable computing environment both today and into the future.

I see this concept appear in discussions surrounding virtualization all of the time.  This is a broader, more general concept but virtualization is the “hot, new technology” facing many IT organizations and seems to be the space where currently we see the “just because you can, doesn’t mean you should” problems rearing their ugly heads most prevalently.  As with everything in IT, it is critical that all technical decisions be put into a business context so that we understand why we choose to do what we do and not blindly attempt to make our decisions based on popular deployment methodologies or worse, myths..

Virtualization itself, I should point out, I feel should be a default decision today for those working in the x64 computing space with systems being deployed sans virtualization only when a clear and obvious necessity exists such as specific hardware needs, latency sensitive applications, etc.  Baring any specific need, virtualization is free to implement from many vendors and offers many benefits both today and in future-proofing the environment.

That being said, what I often see today is companies deploying virtualization not as a best practice but as a panacea to all perceived IT problems.  This it certainly is not.  Virtualization is a very important tool to have in the IT toolbox and one that we will reach for very often, but it does not solve every problem and should be treated like every other tool that we posses and used only when appropriate.

I see several things recurring when virtualization discussions come up as a topic.  Many companies today are moving towards virtualization not because they have identified a business need but because it is the currently trending topic and people feel that if they do not implement virtualization that somehow they will be left behind or miss out on some mythical functionality.  This is generally good as it is increasing virtualization adoption, but it is bad because good IT and business decision making processes are being bypassed.  What happens is often that in the wave of virtualization hype IT departments feel that not only do they have to implement virtualization itself but do so in ways that may not be appropriate for their business.

There are four things that I often see tied to virtualization, often accepted as virtualization requirements, whether or not they make sense in a given business environment.  These are server consolidation, blade servers, SAN storage and high availability or live failover.

Consolidation is so often vaunted as the benefit of virtualization that I think most IT departments forget that there are other important reasons for doing implementing it.  Clearly consolidation is a great benefit for nearly all deployments (mileage may vary, of course) and is nearly always able to be achieved simply through better utilization of existing resources.  It is a pretty rare company that runs more than a single physical server that cannot shave some amount of cost through limited consolidation and it is not uncommon to see datacenter footprints decimated in larger organizations.

In extreme cases, though, it is not necessary to abandon virtualization projects just because consolidation proves to be out of the question.  These cases exist for companies with high utilization systems and little budget for a preemptive consolidation investment.  But these shops can still virtualize “in place” systems on a one to one basis to gain other benefits of virtualization today and look to consolidate when hardware needs to be replaced tomorrow or when larger, more powerful servers become more cost effective in the future.  It is important to not rule out virtualization just because its most heralded benefit may not apply at the current time in your environment.

Blade servers are often seen as the choice for virtualization environments.  Blades may play better in a standard virtualization environment than they do with more traditional computational workloads but this is both highly disputable and not necessarily applicable data.  Being a good scenario for blades themselves does not make it a good scenario for a business.  Just because the blades perform better than normal when used in this way does not imply that they perform better than traditional servers – only that they have potentially closed the gap.

Blades needs to be evaluated using the same harsh criteria when virtualizing as when not and, very often, they will continue to fail to provide the long term business value needed to choose them over the more flexible alternatives.  Blades remain far from a necessity for virtualization and often, in my opinion, a very poor choice indeed.

One of the most common misconceptions is that by moving to virtualization one must also move to shared storage such as SAN.  This mindset is the obvious reaction to the desire to also achieve other benefits from virtualization which, if they don’t require SAN, benefit greatly from it.  The ability to load balance or failover between systems is heavily facilitated by having a shared storage backend.  It is a myth that this is a hard requirement, but replicated local storage brings its own complexities and limitations.

But shared storage is far from a necessity of virtualization itself and, like everything, needs to be evaluated on its own.  If virtualization makes sense for your environment but you need no features that require SAN, then virtualize without shared storage.  There are many cases where local storage backed virtualization is an ideal deployment scenario.  There is no need to dismiss this approach without first giving it serious consideration.

The last major assumed necessary feature of virtualization is system level high availability or instant failover for your operating system.  Without a doubt, high availability at the system layer is a phenomenal benefit that virtualization brings us.  However, few companies needed high availability at this level prior to implementing virtualization and the price tag of the necessary infrastructure and software to do it with virtualization is often so high as to make it too expensive to justify.

High availability systems are complex and often overkill.  It is a very rare business system that requires transparent failover for even the most critical systems and those companies with that requirement would almost certainly already have failover processes in place.  I see companies moving towards high availability all of the time when looking at virtualization simply because a vendor saw an opportunity to dramatically oversell the original requirements.  The cost of high availability is seldom justified by the potential loss of revenue from the associated reduction in downtime.  With non-highly available virtualization, downtime for a failed hardware device might be measured in minutes if backups are handled well.  This means that high availability has to justify its cost in potentially eliminating just a few minutes of unplanned downtime per year minus any additional risks assumed by the added system complexity.  Even in the biggest organizations this is seldom justified on any large scale and in a more moderately sized company it is uncommon altogether.  But today we find many small businesses implementing high availability systems at extreme cost on systems that could easily suffer multi-day outages with minimal financial loss simply because the marketing literature promoted the concept.

Like anything, virtualization and all of the associated possibilities that it brings to the table need to be evaluated individually in the context of the organization considering them.  If the individual feature does not make sense for your business do not assume that you have to purchase or implement that feature.  Many organizations virtualize but use only a few, if any, of these “assumed” features.  Don’t look at virtualization as a black box, look at the parts and consider them like you would consider any other technology project.

What often happens in a snowball effect where one feature, likely high availability, is assumed to be necessary without the proper business assessment being performed.  Then a shared storage system, often assumed to be required for high availability, is added as another assumed cost.  Even if high availability features are not purchased the decision to use SAN might already be made and fail to be revisited after changes to the plan are made.  It is very common, in my experience, to find projects of this nature with sometimes more than fifty percent of the total expenditure on the project being spent on products that the purchaser is unable to even describe the reason for having purchased.

This concept does not stop at virtualization.  Extend it to everything that you do.  Keep IT in perspective of the business and don’t assume that going with one technology automatically assumes that you must adopt other technologies that are popularly associated with it.

In the last year or two we have seen virtualization go from a poorly understood concept to a much-hyped industry buzz word being bantered about constantly in every conversation involving technology.  There is no doubt that virtualization is playing an important role in today’s IT landscape, but the question we are asking is whether virtualization applies to the small and medium business markets at this time.

The quick answer to this question is: absolutely.  Unlike many technologies that are of questionable value or that provide a great degree of technological complication, risk and expense that may not be appropriate for a small business, virtualization is a mature technology (IBM CP/CMS circa 1968) that is well understood and provides a layer of hardware abstraction that can benefit an IT organization of any size and may possibly apply even more to the small business IT department than it applies in the enterprise space.

Before looking at how virtualization can benefit the SMB market I would like to provide some definitions to be sure that we are discussing the same set of technologies.  In today’s IT landscape it has become popular to relabel common technologies as “virtualization” for marketing reasons and this has unnecessarily complicated the issue.

True virtualization refers to the virtualizing of entire operating systems.  Wikipedia uses the term platform virtualization and I will as well.  Technically we could refer to this as “System Virtualization” or “Operating System Virtualization” to distinguish it from loosely-related technologies that may arguably have the right to also use the same general term.

The basic concept of platform virtualization involves running an abstraction layer on a computer that emulates the hardware itself. Through the combination of abstraction and emulation we get what is known as a virtual machine.  This virtual machine is a completely working “computer” onto which we can install an operating system just as if we were installing onto the bare metal of a dedicated machine.  Instead of being limited to only installing one operating system image per computer we can now, with platform virtualization, install many copies of the same or disparate operating systems onto the same piece of hardware.  A powerful concept indeed.

The obviousness of the utility of this technology begs the obvious question: “If platform virtualization has been available since 1968, why is it only becoming popular and important recently?”  This is an excellent question.  The answer is actually quite simple.

Traditional platform virtualization technologies require a lot of support within the computer hardware itself.  IBM has been building this type of support into its mainframe systems for decades and large UNIX vendors like Sun have been providing this in their high-end UNIX servers for years as well.  These systems are highly specialized and typically run their own custom operating system(s).  Generally only large IT shops could afford servers of this magnitude and small shops did not have ready access to these technologies.  For those IT professionals who have worked with this type of equipment in the past the idea of virtualization was often so ingrained into the platform that it was often discussed very little as it was seen as simply an aspect of these high-end server systems and not necessarily a concept in its own right.

What has changed recently is the move to bring platform virtualization to the commodity hardware space occupied by the AMD and Intel (x86_64) processors used by the majority of small and medium businesses as well as larger enterprises.  The first move was to use software alone to make this possible on the x86 processor family.  The early players in this space were VMWare and Microsoft with products like VMWare Workstation, Virtual PC, VMWare GSX and MS Virtual Server.  These products showed that no special hardware was needed to effectively virtualize whole operating systems and began to allow companies of all sizes to experiment with the concept of virtualizing their existing commodity platforms.  This form of virtualization is known as “host-based virtualization” as it requires a host operating system on which the virtualization environment will run.

Following on the tail of these software-only solutions the big processor vendors in the commodity space, AMD and Intel, began building virtualization capabilities into the processor allowing for more flexibility, security and performance and bringing the commodity x64 hardware market much more in line with the traditional offerings from the other processor families common in big iron servers.  By doing so the virtualization market has really exploded both from the vendor side as more and more vendors begin offering virtualization related products and from the customer side as virtualization begins to be better understood and its use becomes more commonplace.  With the latest rounds of purchasing most small IT shops have purchased servers, and often desktops, that support hardware-level virtualization even without intending to prepare themselves for a move to virtualization making the equation often tip in that direction naturally.  This hardware-supported virtualization model is called “hypervisor-based virtualization” as all operating systems run on top of a tiny kernel called the hypervisor and no traditional operating system runs directly on the hardware.

Now that we have a good idea of what platform virtualization is and why it is now available to us as an option we will look at why platform virtualization may be beneficial to us in the small and medium business space.

There are two things that we can readily virtualize (without getting esoteric or starting to virtualize our routing and switching infrastructure) – servers and desktops.  By far the easier and more obvious choice is the virtualization of servers.

Virtualizing the server infrastructure, or part of it, is the first place that most IT shops look today as a potential for virtualization.  Most companies find that the majority of their servers are extremely underutilized with excess CPU, memory and drive capacity sitting idle while additional workloads fail to find a home due to budget constraints, space or implementation time.  Virtualization to the rescue.

Through virtualization we have the opportunity to run several virtual servers on a single piece of server hardware.  We could virtualize just a single server system but this would not gain us any utilization advantages or we could, in theory, virtualize hundreds of servers if our hardware could handle it.  Typically, small businesses can virtualize several typical servers roles onto a single physical server.  Virtual machine density is, of course, determined by load characteristics as well as by the available hardware.  Virtualization uses a lot of memory and storage, obviously, and so careful planning must be made.  Memory and storage are relatively inexpensive today and are certainly vastly less expensive than purchasing additional server hardware and paying to support it.  It is not uncommon for a small business to easily virtualize half a dozen servers on a single piece of hardware at a minimum and a score or more is not an unreasonable number to hope to achieve.

Many small shops instantly jump to the conclusion that virtualization requires expensive SAN storage.  This is not the case at all.  Virtualization provides a range of benefits even without using a SAN storage infrastructure of which shops can take advantage immediately.  There are, of course, some significant advantages available by using SAN in conjunction with virtualization and high availability or load balancing technologies.  Often, though, these high availability and load balancing capabilities are additional features that did not exist prior to virtualization and are not necessary in order for a shop to see significant benefits from virtualization but do present an opportunity for future improvement when and if budgets allow.

Small businesses will see many advantages from virtualization immediately even doing so on a small scale.  Some of these benefits are obvious and some are less so.

Our first advantage is that of hardware cost as I mentioned above.  By eliminating the need to purchase and support expensive server hardware on a per operating system basis we can now deploy more systems at lower cost per system.  In many cases this is not only a cost savings but will also provide greater funds necessary to move from more spartan servers into fewer but more enterprise class offerings with important performance, stability and support features such as integrated power management and KVM over IP from an out of band management console.

Our second advantage is the cost savings from reducing power consumption.  It is very trendy, and for good reason, for companies to be concerned with how “green” they are today and IT virtualization plays a key role in the greenification of the department.  The addition of virtual machines onto a single physical server typically represents a trivial, if even measurable, increase in power draw.  Adding additional physical servers, of course, adds a significant amount of power consumption even for systems that are lightly used or used only occasionally.

Our third advantage is in reducing backup complexity.  Virtualized servers can be backed up using completely traditional methods such as file system level backups from the operating system itself as made popular by traditional backup systems like NetBackup, BackupExec, Amanda, Bacula and others.  So if we desire to stick with current backup strategies we can without any additional complexity, but if we want to move to image-based backups we can do so quite easily.  Using system images as backups is not necessarily new or unique to virtualization but virtualization makes this far more obvious and accessible for many users.  In fact, with virtualization system images (a copy of the entire system, not just of its individual files) can be taken using nothing but the regular filesystem – no special software needed.  A complete system backup can be taken by simply shutting down the virtual server, making a copy of its virtual filesystem – often a single, large file, and starting the system up again.  Restoring a system can be a simple as copying an image file from a backup storage device to the virtual server and starting it back up.  Restore done.  System back online.  This is as simple as it gets.

Our fourth advantage is in the ease of provisioning.  Building a new server operating system directly on hardware is a time consuming venture for most shops.  This is especially true if there are any surprises with new hardware type that has not been used previously.  There may be missing drivers or special operating system settings and parameters needed to support the hardware.  With virtualization the target platform is always identical removing many surprises from this process making it both faster and more reliable.  In many cases deployment is also faster simply because the process of preparing the base machine is so much faster.  To kick off a manual install of Linux on a traditional physical server I must purchase said server, install into rack, connect power and networking, provision networking, turn on server, update firmware, configure out of band management system, burn in hardware, install installation media and begin installing.  Or from some virtualization environments I can simply kick off the entire process with a single command at the command line.  Deploying a new server could go from hours or days to minutes.  This does not even begin to address the simplicity of cloning existing systems within a virtual environment.

A fifth “soft” advantage of virtualization is that there is quite often a significant software cost savings when virtualizing.  Some vendors, like Novell with Suse Linux, allow you to virtualize as many servers as you want on a single physical machine while paying for only a single machine license.  Red Hat gives you multiple installs but not unlimited like Novell.  Microsoft has a range of virtualization pricing options depending on your needs including an unlimited per processor deployment license.  In a worst case scenario you will need to pay for additional operating system and other software licenses exactly as if you were running the same machines physically but in almost all cases there is more pricing flexibility and often dramatic cost reductions for multiple virtualized hosts.

A sixth benefit is in the ability to “roll back” an entire operating system.  Most virtualization platforms allow for a concept of taking a system snapshot, making changes to the active system and then restoring the system back to its original state when done.  This is great for software testing and especially for the testing of operating system patches or any critical update process where something going wrong could cause your system to become unresponsive and potentially not repairable.  The ability to go “back in time” to the latest snapshot, taken seconds before the patch application or risky configuration change can be a lifesaver.  Of course taking an image backup could be used in the same way but snapshots allow for even more rapid recovery due to their “proximity” to the original filesystem.

All of these aforementioned benefits come with a move to virtualization and do not require additional cost for software or hardware.  If our budget allows and the need exists there is also the option of adding one of more virtualization servers and having these servers share a SAN for storage of virtual machine images.  At a minimum this will roughly triple the hardware cost but provides double the processing power and some really amazing features.  The main feature that really makes this solution impressive is the concept of live migration.  Live migration is when a virtual operating system can be moved, while running, from one physical virtualization server to another.  This can be done for purposes of load balancing, disaster testing or to survive a disaster itself.  With some live migration solutions, generally sold as high availability, this migration can happen so quickly that it provides effectively “zero downtime” and even heavily used web servers could survive the loss of a physical server without customers ever knowing that a physical server had gone down.  The transition between virtual machine host nodes is completely transparent to the end users.

There is one major caveat.  Relying upon a SAN in a disaster recovery scenario, of course, creates another point of failure – the SAN system.  So when planning to use SAN to increase the reliability of your virtual machines be sure not to use SAN that is not as redundant or moreso than your servers themselves or you may increase cost while accidentally lowering reliability and performance.

For the average small business it is not unlikely that it will make sense to not only virtualize some of the server infrastructure but virtualize all or nearly all of it.  Virtualization’s advantages are so many and its downsides so few and minor that it is a rare workload in the small business space that would justify dedicated hardware servers.

Now that we have examined why server virtualization makes sense we can begin looking towards desktop virtualization.  Unlike real desktops and servers, virtualized desktops often add a bit of complexity due to licensing requirements especially with Microsoft Windows desktops.

Virtualizing desktops is also somewhat complicated because there are many modes for physically providing desktops.  Obviously once we begin talking about virtualizing the desktop infrastructure we are actually talking about a range of solutions because some device must always exist “on the desktop” providing a keyboard, mouse and monitor which cannot be virtualized and the desktop operating system itself must be running elsewhere.  Even without virtualization this is done (and sometimes marketed as virtualization when, in fact it is simply remote access) very commonly through desktop blades, rackmount desktops or terminal servers.  All of these solutions move the desktop into the datacenter and provide access to it either from thin client front ends or simply via software to remote users existing machines such as users at home logging in to the office.

We will start with the concept of the terminal server as this is the most easily virtualized and the most straightforward.  Whether we are talking about virtualizing the server on which we run Microsoft Terminal Server (now known as Remote Desktop Services), Citrix XenApp or simply a standard Linux remote desktop terminal server we need do nothing more than install that server into a virtual environment rather than into a physical one.  It is really a question of server virtualization not of desktop virtualization – it is only perceived by the end user as being related to their desktops.

The other method of desktop virtualization, “true desktop virtualization” as I will refer to it, is to actually run desktop operating system images on a virtual server just as if they were normal desktops dedicated to a user.  This means virtualizing operating systems like Windows XP, Windows Vista or Windows 7 with each image being dedicated to a single user just as if it was a physical desktop.  We could, theoretically, do the same thing with Linux or some other flavor of Unix but as those systems do not have per user licensing or desktop specific versions and since they always run their desktops in a server mode we would only be able to differentiate between a true virtualized desktop and a Unix-based terminal server in its usage and not by any strict technological means as they are one and the same.  Only Windows truly offers a dedicated desktop model that allows this to happen in this particular manner without the concept of shared access to a single image simultaneously.

Due to licensing restrictions from Microsoft, Windows desktops must be installed one image per user even if technologies exist to make this technologically unnecessary, but still there are benefits to this model.  The big benefits to virtualized desktops definitely go to companies who have employees who roam either internally or even externally.

Using virtualized desktops provides far more control to the company than does providing laptops.  Laptops can be stolen, lost or damaged.  Laptops wear out and need to be replaced regularly.  A virtual desktop that is made accessible from the outside of the company can be secured and protected in ways that a laptop cannot be.  Upgrades are much simpler and there is no concern of the virtual desktop becoming cut off from the corporate network and being unable to be supported by the IT staff.

Almost any worker who uses a computer in the office already has one at home for personal use and often has a  laptop as well in addition to high speed Internet access.  Providing remote access to a virtual desktop at the office therefore potentially incurs no additional hardware expense for the company or staff while easing administrative burdens, lowering power consumption and increasing security.  Some workers will always require laptops but many will not.

For workers still sitting at a traditional desk inside of the company’s offices there is still a need for something physically sitting on the desk that will connect the keyboard, mouse and monitor to the newly virtualized desktop.  This could be an old PC that was planned for retirement, a dedicated hardware thin client or even a laptop.  Internal staff can then move around the office or between offices and sit at any available desk with a thin client and log in to their own dedicated virtual desktop and work exactly as if they were at their own desk.  They can then go home and work from there as well if this is allowed.

Like virtualized servers, desktops, if the need is warranted, can be easily backed up using either traditional means or by simply taking complete system images.  The flexibility is there to do whatever makes the most sense in your environment.

With the complexity and surprise cost of licensing as well as lack of ability to completely do away with hardware on the desktop except for solely remote users, desktop virtualization is hardly the no-brainer that server virtualization is.  Desktop virtualization will require careful analysis on a case by case basis to determine if it will meet the cost and usability needs of the individual organization.  Most organizations who choose to go this route will likely opt to only partially virtualize – using it only in cases where it makes the most sense such as roaming users and remote workers while keeping traditional desktops for those users who would seldom be in a position to take advantage of this technology.  Using terminal server options will often be far more common than “true desktop virtualization” which often makes sense only for power users, developers or to support certain applications that work poorly in a terminal server mode.

There is a final usage of virtualization that warrants discussion if only because it is important to understand its use in the business environment.  This final type of virtualization is not used to put operating systems into the datacenter on server hardware but instead is used to run additional operating system images on traditional desktops and laptops.  This is a common scenario for people who need to test multiple operating systems for support or development.  It is not useful for production systems and is generally outside the scope of this discussion.  It is a highly useful use of the technology but it is rather a niche scenario primarily useful for compatibility testing.

In all of this discussion there has been, somewhat conspicuously, no mention of Apple’s Mac OSX products.  There is a reason for this.  Apple does not license Mac OSX so that it may be virtualized on non-Apple hardware and Apple does not have an enterprise-ready virtualization product ready for its own platform.  The only way to virtualize Mac OSX is to purchase full, additional licenses for each operating system instance thereby eliminating most of the cost benefits of this approach and to run it on a host-based virtualization product such as VMWare Fusion or Parallels which are designed for use on top of a desktop and not as a server-class product.  This is a major gap in the Mac OSX portfolio and one of the ways in which Apple continues to lag behind the rest of the market in capability and in its understanding of its business customers’ needs.  If Apple were to change its licensing strategy around virtualization Mac OSX would prove to be an extremely popular and useful operating system to virtualize both from the server and desktop perspective.

Virtualization is a great opportunity to lower cost and raise productivity while reducing risk for businesses of any size and with budgets as low as zero.  Many technologies promise important improvements for businesses but most create questionable value while incurring real cost.  Virtualization brings real, measurable value while often costing nothing and often reducing spending immediately.  For many businesses virtualization is the technology that they have always dreamed of and is, in fact, available today.