If youve been keeping tabs on virtualization news during the past several months, theres a good chance youve heard about Xen.
Xen, an open-source software project that began its life at the University of Cambridge, aims to virtualize operating system instances and to do so better than current options such as VMware Inc.s products.
Rather than re-create a machine within which any operating system may run, Xen takes a "paravirtualization" tack—entire operating systems may run atop Xen, but their kernels must be modified to do so.
This approach means less operating system flexibility than you get from VMware; for example, Windows wont currently run on Xen. But the reduction in overhead incurred by running virtualized instances—as well as the projects free GNU GPL (General Public License)—has generated quite a bit of interest.
While Xens future seems bright, its present is somewhat murky. The next major release of Xen, Version 3.0 (the current stable release is 2.0.7), has been held up for months.
Version 3.0 will support Advanced Micro Devices Inc.s AMD64 architecture, symmetric multiprocessing, guest operating systems and a set of other features. Prerelease code is now available, but discrepancies between this prerelease code—which Red Hat Inc.s Fedora and Novell Inc.s SUSE Linux ship with—and the 2.x code—which Debian is targeting—have further clouded the Xen waters.