Sun has upgraded one of its most popular freeware products after releasing a major new version of its open-source virtualisation tool xVM VirtualBox, which includes the ability to cope with demanding server workloads.

VirtualBox proved popular when it first appeared back in 2007 from Stuttgart, Germany-based Innotek. Sun later acquired Innotek in February 2008. At the time, Sun revealed that the product had been downloaded over four million times, but Sun now says it has surpassed 14.5 million downloads and 4 million registrations worldwide, as well as more than 25,000 downloads a day.

So what is VirtualBox? Well, it is a x86 virtualisation product designed for both enterprise and home use. Essentially it is both a desktop and server-virtualisation hypervisor, and is freely available as open source software under the terms of the GNU General Public License (GPL).

It runs on Windows, Linux, Macintosh and OpenSolaris hosts, and supports a large number of guest operating systems including Windows (NT 4.0, 2000, XP, Server 2003, Vista, Windows 7), DOS/Windows 3.x, Linux (2.4 and 2.6), Solaris and OpenSolaris, and OpenBSD.

Put simply, if a user downloaded and installed VirtualBox onto their laptop, they could then run most any other popular operating system on the same machine besides its native OS. Or they could run several operating systems at the same time, depending on what hardware resources are available.

This makes it an incredibly useful tool for software developers who want to target multiple operating systems in order to maximise their audience and return on investment (ROI). VirtualBox gives them the opportunity to run things such test environments etc, on a single laptop for example.

Back in September last year, Sun said it had improved VirtualBox's performance and platform support when it released VirtualBox 2.0. But now the company has released a major upgrade, version 3.0, which it says offers improved desktop and server virtualisation features.

On the desktop side, it can now run Microsoft Direct3D support for Windows guests, which allows for graphically intensive Windows applications, such computer modelling, 3D design and games software, to run in a virtual environment. Support for version 2.0 of the Open Graphics Library (OpenGL) standard has also been added, which allows for high performance graphical applications that typically use graphical hardware acceleration. Finally, support for a wider range of USB devices, such as iPods, mobile phones and storage devices has also been added.

But it is on the server side, which has seen the most significant updates. With more and more multi-threaded database and web applications making use of multiple CPUs, VirtualBox 3.0 can now support virtual SMP systems with up to 32 virtual CPUs (vCPUs) in a single virtual machine. This now gives VirtualBox the ability to run ‘heavyweight data-processing workloads.'

The hypervisor has also been enhanced for SMP to enable optimum performance, and the API platform, designed to be the basis of the VirtualBox Web Console project has also been updated. According to Sun, the Web Console project is coming soon and should allow IT administrators to manage their data centres from a web console.

"The rapid evolution and proliferation of VirtualBox software continues," said Jim McHugh, VP of marketing, data centre software at Sun, in a statement. "With each new version, VirtualBox software delivers more innovation, performance and power. And as virtualisation continues to gain momentum in the market, the world's developers and IT decision makers are turning to VirtualBox en masse."

As already mentioned, VirtualBox software is free of charge for personal use. However for wider enterprise deployments, enterprise subscriptions are also available, starting at $30 (£18.61) per user per year. The enterprise version includes a 24/7 support, and discounts are available based on volume.

Sun did not respond to an interview request at the time of writing.