Desktop virtualization for Windows and Linux heats up

Desktop virtualization is one of those technologies that confound the experts. Just when you think you've got it figured out, along comes some interloping development to upset the apple cart. Most recently, that role has fallen to Sun's VirtualBox, the plucky open source VM solution that's quickly gobbling up the general-purpose desktop virtualization space left vacant by Microsoft and VMware. Users from the three major platforms -- Windows, Mac OS X, and Linux -- are flocking to VirtualBox for its scalability, robust networking, and bargain price point (it's free).

Meanwhile, VMware continues to steer its flagship Workstation offering away from the general-purpose space and toward its lucrative niches in the software development, help desk operations, and server virtualization and VDI support markets. At the same time, Parallels has finally seen fit to deliver a version of Parallels Desktop for Windows that's on par with its Mac product, complete with USB device integration, bridged networking, and guest OS SMP support. And up in Redmond, the sinewy remains of the once proud Virtual PC continue to wither away as Microsoft completes the product's transformation from versatile VMware challenger to brain-dead host for Windows 7's Windows XP Mode compatibility layer.

[ Parallels Workstation 4 Extreme's support of Intel's Virtualization Technology for Direct I/O on Nehalem-based workstations delivers near native performance for graphics, disk, and network I/O. Read the review. ]

Taken together, these developments represent the biggest shake-up for desktop virtualization in years. There's some genuine innovation going on, especially in the areas of hardware support and application compatibility. VMware Workstation, Parallels Desktop, and VirtualBox all support 32- and 64-bit Windows and Linux hosts and guests, and all have added compelling new VM management capabilities, ranging from automated snapshots to live VM migration. Read on to see which products hit their marks, which overachieve, and which seem to miss the boat entirely.

VMware Workstation 7 VMware Workstation has long been the gold standard of desktop virtualization. Powerful and sophisticated, yet easy to use, this pioneering tool sets the bar for solutions addressing this niche product category. In fact, VMware Workstation has been so far out in front for so long, it's hard to imagine a world in which this bellwether product isn't the class leader in virtually every category.

Yet in the past few weeks, the unthinkable has happened: VMware shipped a new version, VMware Workstation 7, and it wasn't the class leader, at least in terms of scalability -- and perhaps ease of use or, for that matter, overall value.

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In terms of scalability, VMware has been eclipsed by Sun Microsystems, which is now shipping a version of VirtualBox that supports up to 32 virtual CPUs per guest OS. Similarly, VMware's lead in usability is being challenged by Parallels, which has finally brought the ease of use of its award-winning Parallels Desktop for Mac product to the Windows platform. And since both solutions are significantly cheaper than Workstation 7 (Parallels Desktop 4.0 for Windows retails for $79.99, while VirtualBox is completely free), they've backed VMware into a corner that seems to be getting smaller and smaller.

Fortunately for VMware, that corner is still a highly profitable one, populated by vertically oriented users who have very specific needs that only VMware Workstation can fully address. These include professional software developers who need tight IDE integration across a range of development platforms, help desk professionals who want to be able to quickly build and prototype troubleshooting simulations of end-user environments, and of course, anyone who supports and manages a VMware-based server farm or VDI deployment where technologies like VMware View 4 and ACE are prevalent.

It's to these users -- the proverbial "choir" -- that VMware is preaching with Workstation 7. Features like support for Windows Aero Glass, in VMs running Vista or Windows 7, are geared toward help desk personnel who need to more accurately replicate end-user desktops, while automatic (timed) snapshots, expanded Replay debugging, and deeper IDE integration features help to reassert the product's stranglehold on the ISV crowd. Even core changes, like the ability support up to four virtual CPUs per VM and to host vSphere 4 as a guest platform, are targeted at the company's bread-and-butter, server-consolidating and VDI-loving customer base.

Clearly, VMware no longer views the traditional desktop virtualization space as competitive -- at least, not outside of areas where it intersects with broader virtualization themes. This is the sort of complacency that market leaders get to enjoy, but it's also a double-edged sword: VMware's decision to effectively ignore the competition has allowed sleeper products, like the scrappy VirtualBox, to nibble away at the fringes of its user base. And while VMware may dismiss impressive technical feats, like 32-way virtual CPU support, as mere academic exercises (who really needs 32 CPUs in a desktop VM?), the fact that they're being accomplished by someone else, when you're the perceived market leader, is never a good sign.

VMware Workstation 7 now lets you differentiate between logical CPUs and CPU cores when configuring virtual processors for your VMs.

In the meantime, loyal Workstation users will be pleased by the incremental enhancements that version 7 brings. During my own testing, I was impressed by Workstation 7's deft handling of virtual printing support, which is now almost entirely automated. Plus, the capability to automatically snapshot my running VMs at timed intervals gave me more confidence to push my various test scenarios, understanding that any catastrophic failure could be rolled back quite easily.

I also found Workstation 7's take on virtual CPU support interesting. Instead of merely exposing a bunch of generic x86 compute engines, Workstation 7 allows you to present a more refined view to the guest OS by letting you specify whether they appear as discrete CPUs or as multiple cores within a single CPU. This distinction is important because it affects how more recent operating systems, including Windows 7 and Windows Server 2008 R2, interact with CPU resources. These latter-day OS support core parking and generally tune their scheduling algorithms to match the underlying processor core configuration.

Overall, VMware Workstation achieves its goal of delivering more red meat to its primary customer base: help desk operators, professional developers, and vSphere and VDI support personnel. Technical challenges from plucky open source upstarts notwithstanding, Workstation remains the gold standard in desktop virtualization.

Parallels Desktop 4 for Windows and Linux When I last looked at a Parallels solution for Windows systems, the product in question was just a pale imitation of its better-known sibling, Parallels Desktop for Mac. Parallels Workstation for Windows, as it was called back then, delivered good basic desktop virtualization but lacked critical functionality like USB device support and bridged networking.

Locked in a death struggle with VMware on the Macintosh platform, Parallels allowed its Windows version to languish for nearly two years while it focused on defending its Mac OS X flagship. Then, this past summer, Parallels surprised everyone by bringing forth Parallels Desktop 4 for Windows, a product that was on par functionally with Parallels Desktop for Mac -- at least for a time.

Parallels Desktop 4 for Windows and Linux lets you assign up to 8GB of RAM to each VM and sports the same user-friendly interface as its Mac cousin.

The subsequent availability of Parallels Desktop 5 for Mac once again puts the Windows version behind its favored sibling in terms of functionality. For example, while the Mac version supports popular features such as Windows Aero Glass, the Windows version is still stuck running the Aero Basic theme, which puts it at a competitive disadvantage to VMware Workstation 7.

Fortunately, Parallels 4 still has enough redeeming features to stand on its own. For example, you can now create virtual machines with up to 8 virtual CPUs and 8GB of RAM. Automated installation scripts (similar to VMware's Easy Install mechanism) now take the pain out of installing and configuring new Windows-based VMs. And an improved snapshot feature makes it possible to set up timed snapshots of a VM's state -- useful for rolling back changes or repairing a VM after a crash or malware incident.

[ Parallels Workstation 4 Extreme's support of Intel's Virtualization Technology for Direct I/O on Nehalem-based workstations delivers near native performance for graphics, disk, and network I/O. Read the review. ]

Another useful feature is the ability to save a cloned image of a VM as a template that can be reused as the basis for new VMs. This is handy when you need to create a number of VMs with similar baseline configurations and want to avoid the repetitive installation steps common to each VM.

Based on the nature of these new features, it seems clear that Parallels was targeting VMware Workstation for Windows with this new release. The Easy Install clone, timed snapshots, and templates are all responses to features that are present in VMware Workstation. And while they serve to bring Parallels closer to parity with previous versions of Workstation, the reality is that VMware Workstation is itself a moving target.

Yes, Parallels Desktop for Windows now supports more virtual CPUs per VM than VMware Workstation, but it makes no distinction between discrete processors or cores, and Parallels also requires a system with hardware virtualization support in order to run its VMs. (VMware and VirtualBox support both hardware virtualization and legacy binary translation, allowing them to run on systems lacking Intel or AMD hardware-assisted virtualization technology.) And while Parallels Desktop now has a timed snapshot feature, it's not as granular or as sophisticated as VMware's pioneering Replay function, which has been a staple of Workstation since version 6.

Overall, Parallels Desktop 4.0 for Windows and Linux is a solid product for customers in need of a traditional desktop virtualization solution. It's fast, easy to use, and great for those who need to run multiple operating systems. The problem is, almost nobody is looking for such a solution anymore -- at least, not on the Windows platform. Unlike with the Mac, where virtualization is essentially a lifeline technology, on Windows it's more of a niche application, a stopgap measure for legacy compatibility.

So while VMware focuses its energies on lucrative vertical markets, Parallels seems stuck looking at the world through the prism of Mac OS X. And as with most things hailing from within the Apple Reality Distortion Field (RDF), Parallels' perception of what Windows users want (and are willing to pay for) is clouded by too much fruit in the diet.

Sun VirtualBox 3.1 Everyone loves a freebie. Whether it's free beer, a free checking account, or a free-because-you-paid-to-attend tablet PC at a tech conference, getting something for nothing always feels good. However, none of us expects these freebies to be of a particularly high quality. The beer is watered down, the checking account has hidden strings attached, and that tablet PC is either underpowered, loaded with crapware, or both.

So when we do come across a genuinely compelling freebie, we tend to shout its name to the rafters. And after years of wallowing in obscurity, VirtualBox -- the desktop virtualization solution of choice for FOSS groupies and similar anti-establishment types -- is causing quite a ruckus.

[ VirtualBox is one of InfoWorld's "Top 10 tools for IT pros" and among InfoWorld's top picks for "The best free open source software for Windows." ]

It all began when Sun Microsystems acquired the product from little-known German developer Innotek. With Sun's engineering resources behind it, VirtualBox quickly grew from its role as "the little VM solution that could" to today's technology leader in desktop virtualization scalability and manageability. In fact, VirtualBox has evolved so quickly, it's almost hard to recognize it anymore. Features like 32-way virtual SMP support are unrivaled, while the inclusion of branched snapshots finally brings it on par with its commercial competitors.

But the real shocker with VirtualBox 3.1 is the capability to dynamically move running VMs between VirtualBox host systems. Similar to VMware's VMotion technology, this new feature, which Sun has dubbed "Teleportation," adds a whole new wrinkle to the VirtualBox story. Suddenly, this once shy, awkward desktop VM solution is sporting speeds and feeds that seem more at home on a VMware ESX or Microsoft Hyper-V datasheet.

VirtualBox 3.1 supports up to 32 virtual CPUs per VM and has a much-improved snapshot mechanism with full branching support.

All of which begs the question: Just what the heck is Sun up to with VirtualBox? It's one thing to round out a product's capabilities to make it more competitive. But this latest development takes VirtualBox in an entirely new direction, one that leads directly to the corporate datacenter and the lucrative rack space turf carved out by the commercial virtualization heavyweights. If VirtualBox proves to be as capable and scalable as its latest incarnation seems to indicate, it could have a dramatic effect on the balance of power among the raised floors set. After all, nothing upsets the apple cart like an unexpected interloper offering free produce.

In the meantime, VirtualBox's loyal fan base can smile knowing that there's some serious VM muscle lurking underneath their favorite product's pedestrian exterior -- something that an Innotek executive intimated to me years ago. At the time, I dismissed his comment as nothing more than prideful boasting. However, I now see that this guy wasn't kidding, and that Sun's decision to gobble up this diamond in the rough is looking less like a compatibility play for OpenSolaris and more like a clever way to acquire a potentially class-leading VMM (Virtual Machine Monitor) with which to pry loose VMware's stranglehold.

Kudos to Sun for seeing VirtualBox's potential and for keeping it FOSS so that the rest of the world can enjoy the benefits of its robust virtualization engine. This is one freebie that breaks the mold and delivers more, not less, than you're expecting.

  • Excellent help desk and software developer features
  • Improved scalability and performance
  • Tight integration with VMware vSphere
  • Good scalability and performance
  • Easy-to-use interface inspired by Mac version
  • Some advanced features, including timed snapshots
  • Excellent scalability and performance
  • Improved usability, including branched snapshots
  • Teleportation feature shows off underlying VM muscle
  • No longer leads in scalability
  • Expensive
  • Value proposition challenged by the free VirtualBox
  • Requires host with hardware-assisted virtualization
  • Not as easy to learn and use as VMware Workstation or Parallels Desktop
  • IDE integration biased heavily toward open source tools

This story, "InfoWorld review: Desktop virtualization for Windows and Linux heats up," was originally published at InfoWorld.com. Follow the latest developments in virtualization, Windows, Linux, and open source, including the latest InfoWorld Test Center reviews, at InfoWorld.com.

This story, "Desktop virtualization for Windows and Linux heats up" was originally published by InfoWorld.

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