While server virtualization approaches offered by VMware, Microsoft, Xen, Parallels, Serenity Virtual Station, SWsoft are more or less understandable for potential customers, Virtual Iron, present on the scene since 3 years, has never been completely clear and the just announced Virtual Iron 3.0 for Xen could make things even more confused. Virtual Iron entered the market 3 years ago, providing a virtualization technology comparable with VMware one. The company became famous mainly for the additional feature of server aggregation: the capabililty of clustering several physical hosts, to provide a distributed virtualization hypervisor. Today Virtual Iron is abandoning its proprietary virtualization stack to adopt and enrich the open source Xen hypervisor. This doesn't mean Virtual Iron is offering just a set of enterprise management features around Xen, competing against XenSource (at least if they are still on the known mission), Red Hat, Novell and all others trying to add value to the hypervisor. Virtual Iron has replaced the Xen dom0 with an in-house developed one, called Open Virtual Layer and distributed with GPL license, enhancing it to provide unique features like 64bit and 32bit virtual machines concurrent run capability, unmodified Microsoft Windows guest operation system run capability, and improved performances. (if you are interested in take a look at Xen 3.0 architecture here) While it's true that Virtual Iron 3.0 needs virtualization aid from AMD/Intel modern CPUs (and won't work at all without them), it's the first real Xen-based implementation able to compete against VMware and Microsoft with Windows virtualization, featuring para-virtualization performances and something upcoming ESX Server 3.0 and Virtual Server 2005 R2 still cannot provide: 32bit / 64bit VMs mixed environment support. For free in some cases, revaling with upcoming VMware Server and to be repriced today Virtual Server 2005 R2. What this means for the virtualization market? At least 4 things:

• Xen has now a real chance to demonstrate how good is the para-virtualization approach outside research laboratories and small testing environments
• A serious VMware competitor for enteprises could be finally arrived, obliging them to reduce ESX Server prices
• Several companies, with enough know-how could try to do the same, as soon as new AMD/Intel CPUs become widely deployed
• Microsoft, with the accumulated delay in planned Windows Hypervisor (codename Viridian), could have to face an even more competitive market than expected