Microsoft Wednesday released a feature-complete beta of its Hyper-V virtualization technology, which is an add-on to Windows Server 2008.

Microsoft said the "Release Candidate" (RC) was "near-final" code and included updates from the beta that shipped in late February when Windows Server 2008 was released.

The code is due to became available after 10 a.m. PDT on Microsoft's Web site.

A release candidate is final beta before the code is considered finished. The company said it was on track to ship Hyper-V, which has gone through numerous delays, by August. It is unclear if the company plans another RC version before then.

Jeff Woolsey, senior program manager on the Microsoft virtualization team, used a question mark on his blog in referring to the beta as "Hyper-V RC?" He also added, "We're in the home stretch now..."

With Hyper-V's shipment Microsoft will add a third hypervisor option to go along with those already available from VMware and Xen-based derivatives marketed by Citrix, Oracle, Red Hat and Novell. Hypervisor technology is a base technology layer that acts as the virtualization foundation for guest operating systems.

In this newest beta, Microsoft has added support for new guest operating systems that can run on top of Hyper-V: Windows Server 2003 SP2, Novell SUSE Linux Enterprise Server 10 SP1, Windows Vista SP1 (x86), and Windows XP SP3 (x86).

The company also said users can install the Hyper-V Manager snap-in to the Microsoft Management Console on Vista SP1 (x86 and x64). The snap-in allows for remote management of Hyper-V.

On the performance front, Microsoft said the virtual machines using pass-through disks will see a performance improvement over previous versions, and that installing the software via a network has been improved. (See 20 most useful Microsoft sites for IT pros.)

Woolsey says the three most common roles virtualized among early adopters are IIS, application server and Terminal Services, and that the four most deployed Microsoft applications are SQL Server 2005 and 2008, Exchange Server and Forefront. He said more than half are running an antivirus/security application, nearly 50 per cent are running a backup appliance, and approximately 75 per cent are running Hyper-V with some attached storage.

Hyper-V is the foundation of Microsoft's virtualization strategy, which also includes Systems Center Virtual Machine Manager (VMM), which helps maximize physical server utilization, and centralizes management and provisioning of virtual machines.

The version of VMM that supports Hyper-V is expected to ship in the second half of this year.

Microsoft has been trying to keep its virtualization technology on people's minds lately. It made a big announcement in November that it would offer a standalone version of Hyper-V that does not require the use of Windows Server 2008. This was a 180 degree turn from Microsoft's original position that virtualization is something that ships with the operating system.

Just last week, Microsoft acquired desktop virtualization vendor Kidaro. Microsoft plans to add Kidaro's software to its Microsoft Desktop Optimization Pack, which is only available to users with Software Assurance maintenance contracts.