Virtualization is hot because its so useful. As if that wasnt enough, the word "free" frequently now accompanies virtualization, but, as weve come to understand, free can mean many things.
To take a couple of pages from the open-source software glossary (and to add one of our own), free virtualization technology can be categorized into three buckets: free as in beer, where the software is free to use but the code remains closed; free as in speech, where the software may or may not carry a charge but can be freely modified and redistributed; and free as in Internet Explorer, where the software is free but only with a valid license for another application (in IEs case, Microsoft Windows).
Not surprisingly, "free as in IE" is the road that Microsoft has chosen for its virtualization technologies. On April 3, during LinuxWorld in Boston, Microsoft announced that it was dropping the cost of its Virtual Server 2005 Release 2 product—from the already-low $100-to-$200 range to free.
We werent surprised by this move, since VMware had announced that it would be offering its VMware Server for free. Unlike VMwares products, however, Microsofts Virtual Server runs only on Windows, so it still carries license fees.
Moving forward, Microsoft will continue along the free-with-purchase track when it builds its own hypervisor technology, code-named Viridian, into a version of Windows due somewhere in the fairly far-off, post-Longhorn Server time frame (possibly as late as 2009, according to some reports).
While Microsoft appears set to go it alone, wed love to see the company do itself and its customers a big favor by joining in on the virtual infrastructure barn raising that the Xen hypervisor project has become. Xen, while not yet as fully baked as competing products, at least currently exists in a usable form.
And ditching Viridian for Xen as the engine of the Windows hypervisor might speed development enough for Microsoft to deliver higher-performance virtualization functionality in time for Longhorn Server.
The Xen hypervisor, which enables Linux and some BSD (Berkeley Software Distribution) systems to host virtualized operating system instances, is licensed under the GNU GPL (General Public License) and is free to acquire, distribute and modify.
Xen, plus a freely available operating system (such as OpenSUSE, Fedora or Debian), can add up to a license-fee-free virtualization solution. However, the relative immaturity of Xen, which shows particularly in the management and administration tools that are currently available for it, means more implementation costs.
We expect Xen to stand better on its own in the future, as open-source software-producing companies build up a stable of tools to complement it. Red Hat and Novell have already folded Xen into some of their distributions, and both companies have announced their intention to make Xen the centerpiece of their operating system virtualization offerings.
Last year, VMware caught our attention by releasing a free application for running the VMs (virtual machines) created with the companys Workstation, GSX and ESX Server products—the VMware Player. Shortly thereafter, VMware raised the stakes by announcing that VMware Server, the follow-on to its $1,400 GSX Server product, will also be available free of charge.
Not only do these moves stand to broaden the market for virtualization products and services, but they also may help VMwares VM format become an industry standard (as Adobe Acrobat Reader has done for PDF).
At the end of 2005, SWsoft released the core of its operating-system-level virtualization product, Virtuozzo, under the GPL and created the OpenVZ project. OpenVZ resembles the Containers feature in Sun Microsystems (freely available) Solaris 10 operating system in that both technologies allow multiple instances to run under a single host kernel. OpenVZ lacks the breadth of management tools of its proprietary elder sibling, but we expect to see availability improve as the project matures.