Of all the features being introduced into Linux server technology, virtualization stands out as one of the most significant, due to its growing pervasiveness as well as the opportunity it provides Linux for becoming a more dominant player in the data center.
Depending on how it's implemented, virtualization can allow multiplatform applications to be run off of a single, underlying operating environment. Beyond Windows, Sun's Solaris also presents competition to Linux as an underlying environment.
But this year, major customer implementations of Linux virtualization really got underway in earnest. Nationwide Services Company, for example, swapped out more than 700 Intel and Unix servers in favor of two refrigerator-sized mainframes running Novell's SUSE Linux in VMWare.
In December, the Charlotte Observer, a major daily newspaper, announced plans to use virtualization management software from Virtual Iron in migrating a trio of applications from Unix to Linux, including an Oracle-based circulation database.
Some analysts suggest, though, that virtualization is still getting delayed somewhat by user confusion over the term. Experts have defined a variety of different approaches to virtualization, including emulation, in which the virtual machine simulates the complete hardware; native virtualization, in which the VM simulates only enough of the hardware to allow operation of an umodified OS in isolation; paravirtualization, where the VM provides a special API requiring OS modifications; operating system-level virtualization; and application virtualization.
New virtualization products for Linux did become available in 2006, with others presumably on the way for 2007. Novell, for example, talked up the virtualization-enabled SUSE Linux Enterprise Server (SLES) , along with two new desktop products, at its annual BrainShare conference in March.
The final shipping SLES 10 product saw release last summer, several months prior to the company's November announcement of its agreement with Microsoft and the subsequent launch of the Novell/Microsoft/Sun-led Vendor Interop Alliance.
Among its many other provisos, Novell's deal with Microsoft calls for the two companies to work together on interoperability across areas that include virtualization, Web services, and document translation technology.
But getting back for a moment to an existing product, on the virtualization side, SLES 10 comes with built-in Xen 3.0 [open source hypervisor] technology. Other features include a more capable YaST (Yet Another Setup Tool) installer; application security tools known as AppArmor; a new-GNOME-based front end; and updated editions of several applications. The applications include Apache and Cyrus IMAP mail services 2.2; MySQL 5.0; PostgreSQL 8.1, for instance.
Red Hat, for its part, first introduced the Xen virtualization engine into Fedora. The vendor had hoped to get the virtualization-enabled Red Hat Enterprise Server (RHEL) 5 to market by the end of 2006, too.
The final edition of RHEL 5 didn't make the end-of-year milestone. In November, however, Red Hat released beta 2 of the software server, less than one month after the release of Fedora Core 6.
In an interview with LinuxPlanet at C3 Expo last summer, one Red Hat official said that, along with work done in the open source community around Xen virtualization, RHEL 5 would also include the first elements of "statelessness" derived from Fedora Core.
Nick Carr, Red Hat's enterprise marketing manager, also said that RHEL 5 beta 2 with Fedora Core, then slated for availability in September, would give a good general idea as to which features would be included in the final shipping product of the software server.
Also at C3 Expo, Transitive, Inc. stepped into the virtualization arena with the announcement of two products for migrating Solaris/SPARC applications from the version 2.6 era onward to Linux. Transitive's products will initially support Red Hat and Novell's SuSE Linux only, but support for other Linux distributions might follow, according to Gal Chanoch, the company's director of marketing. In November of this year, Transitive shipped the first of these virtualization products.
In April, two-year-old Virtual Iron released version 3.0 of its VM, an edition that adds Xen as well as support for Intel Virtualization Technology, a set of hardware-assisted capabilities built into Intel processors. By using Intel's technology, Virtual Iron has also added Windows support to its previous support for Linux.
Other smaller players in the Linux virtualization ring include start-ups such as Trigence and SWSoft. Trigence, a company that first launched at the Demo show this year, makes virtual application software designed for migrating applications while you move from Red Hat to Novell (or the other way around), or while you upgrade from one version of Solaris to the next.
SWSoft produces Virtuozzo, an increasingly popular virtualization environment, based on the OpenVZ open source project, that lets multiple applications operate on either a Linux or Windows host.
But in terms of Linux servers themselves, Novell and Red Hat are not the only games in town. In September of this year, for example, French-based Mandriva Linux released a virtualized server that also represents the company's first business server.
Among its many marks of distinction, Mandriva Corporate Server supports not just one, but three major virtualization engines: Xen, VMWare, and OpenVZ.
Will Novell's new alliance with Microsoft give SUSE Linux a competitive advantage over other Linux servers? Only time will tell.
But according to some observers, virtualization should get easier in the future, anyway, when the next edition of the Linux kernel is released. The 2.6.20 kernel will include a new capability known as Kernel-based Virtual Machine (KVM).
This article was first published on LinuxPlanet.com.