It also introduced the masses to the notion of desktop virtualization.
, until recently, has focused largely on the server, where the idea of enabling one server to act as many has clear cost benefits.
While Windows-on-a-Mac is still the most widely known use for the technology, there are reasons why desktop virtualization may soon expand into new areas.
So far, many of those areas are in the corporate arena, where businesses are aiming to offer more secure environments or perhaps run older in-house software that only works with older operating systems, while at the same time having desktops running modern operating systems. It also has benefits in terms of disaster recovery, provided the virtual machines are well backed-up.
There are two main ways of doing desktop virtualization. One is to run multiple operating systems on one PC. Another is to have one or more operating systems running on a remote server, with the desktop tunneling in to those other operating systems. Technology such as Microsoft's Remote Display Protocol pipes keystrokes and mouse clicks to the server and a view of the screen back to the user.
offers technology for both desktop virtualization approaches. Its Virtual Desktop Infrastructure takes the server-based approach, while two other options handle things directly on the desktop, one for power users and the other for standard cubicle dwellers.
Its workstation product is geared for power users such as administrators who want to test software patches before distributing them across a company, said Jerry Chen, senior director of enterprise desktop software at VMware. Chen himself uses it to run three separate virtual machines: one for work, one for home and one for his Slingbox video player.
The one geared for standard users enables corporate administrators to provide locked-down desktop software, for example prohibiting use of printers or flash memory drives in cases where sensitive data is involved. It also lets the user pack up the virtual machine on a flash drive and continue working with it on another PC, provided that computer is capable of running a virtual machine.
Virtual machines could also prove useful in the home, letting a physical machine be carved into each family member's "own PC." Nowadays, typically each member has a separate user account to segregate the programs and data, but a virtual machine would prevent, say, junior from wiping out dad's PC with a virus downloaded from some file-sharing service.
Start-ups entering the fray
While VMware is the dominant player, there are plenty of contenders in the desktop virtualization industry.
Citrix, which has years of experience with thin-client software,
And other start-ups are preparing to enter the fray. Qumranet, sponsor of the open-source
Microsoft also sees desktop virtualization, in its many forms, gradually becoming more popular among general users, but general manager Mike Neil noted that the technology is still probably "a ways from (being used by the) majority of mainstream users.
The company was an early player in desktop virtualization,of Connectix back in 2003. The company has since made that product largely free, but chose not to participate in the Windows-on-Mac space, an area where Virtual PC was once the only game in town. On the PC side, though, there have been 2.5 million downloads of the product since February, with IT departments being among the most common users of the technology.
Others, including Intel, have proposed running security and management software in an administrative virtual machine that runs alongside a PC's regular operating system. It could, for example, monitor network traffic to guard against the spread of a worm.
Another idea is to use a virtual machine to segregate work and personal applications on a PC, allowing businesses to separate their corporate environment from personal applications, such as iTunes.
One of the challenges of desktop-based virtual machines is the fact that there has to be enough memory to run both the host operating systems and any guest operating systems.
In theory it might be nice, say, to run one's online banking application in a virtual machine that is entirely secured from the rest of the operating system. Memory requirements, though, make that impractical at this point, Neil said.
"That's a pretty significant tax to pay to do that," he said.
VMware is trying to make installing new virtual machines less onerous. Last week,that began firing up a 410MB virtual machine when only a fraction of it had been downloaded.
Server-based virtual desktops, meanwhile, aren't necessarily completely interchangeable with regular PCs, though. For example, Microsoft's RDP doesn't currently support audio. Corporate IT might be happy that users aren't likely therefore to spend a lot of time watching YouTube videos, but audio support also is important for work tasks such as Webcasts or Internet telephony conversations.
Frank Sabatelli is a big fan of running virtual desktops on servers. As vice president of virtual engineering at financial services firm iQor, he has to set up new offices with hundreds of PCs for the call center services the company offers to clients such as credit card firms.
"We had technicians in the field who would have to redeploy 500 or 600 machines in a couple weeks," but the company couldn't keep up with competitors, Sabatelli said in a discussion at thein San Francisco Tuesday. With virtual desktop software from VMware, deployment of such an office takes 48 hours. "We got it down to under 8 minutes per machine," he said.
One complication of virtual desktops is software licensing--in particular, Windows licensing. Only some versions of Windows may be installed on multiple virtual machines, and even then, moving a virtual machine from one machine to another poses complications.
"You could probably get a Ph.D. in Windows licensing," quipped one executive who has to reckon with the issue.
Matt Levine, a Web developer for blog-monitoring site Technorati, said his company makes extensive use of Parallels and of VMware's rival Fusion product for testing its site. "We're able to simulate different computing environments and different browser environments that our users are going to be using," Levine said. That vastly accelerates testing of new features, especially given that Internet Explorer 6 and 7 can't be installed simultaneously on the same machine, he said.
Virtual desktops are a natural fit for one company: Sun Microsystems, which has for years advocated the idea of moving as much processing power as possible to central servers. This week, Sun announced Virtual Desktop Infrastructure Software 1.0, which goes on sale in October and incorporatesand other products.
Sun's $149 software acts as a middleman that transports information from thin clients or PCs to the central servers' virtual desktops and back. It can use VMware's virtual desktop software, connecting its PCs via Microsoft's transport mechanism or Sun's own technology--which, unlike Microsoft's, supports audio.
Parallels, too, is hoping not to be left behind in the Windows and Linux worlds.
The company is looking to bring over to its Windows-based program some of the consumer features it has on the Mac, such as Coherence, which allows programs from guest operating systems to appear as if they are native to the host operating system.
Although the Mac is obviously where the most demand is today, Parallels spokesman Benjamin Rudolph said that as Linux gains ground, there may be more reasons to run it alongside Windows.
Desktop Linux is coming, he said. "It may not be the huge spike that people predicted five years ago, but it's coming."
Virtualization means that people don't have to switch entirely to a different operating system. If people find even one Linux application that they really want to run, desktop virtualization can make that feasible.
Rudolph said virtualization also enables people to try out things that they might otherwise be afraid to try. An early beta version of a program or some other questionable application can be installed in its own virtual machine. If it works, great. If not, just delete the virtual machine.
"It's the ultimate pen with eraser," he said.