With the Windows-based edition of Parallels Server currently in beta, Parallels announced on Wednesday that another of its virtualization servers, Virtuozzo Containers, will run on HP's high-end, Windows-based Integrity servers.

On Tuesday, Parallels' desktop virtualization software for Mac formed a key part of the launch announcement for the Enterprise Desktop Alliance (EDA), a new group established to promote better management of Macs in multi-vendor environments.

"The two announcements are separate, of course," said Bryan Goode, Parallels' director of business development, in an interview on Wednesday evening with BetaNews.

As Goode sees things, there's an unifying thread to the two announcements: that Parallels -- a company that also produces server automation software, and virtualization software for Mac OS and Linux -- is now putting more and more emphasis on various sorts of virtualization.

Like Parallels' desktop virtualization software, which runs Windows on top of Mac OS, the company's new Parallels Server uses a hypervisor approach, whereas Virtuozzo Containers is based on container technology, he told BetaNews.

In contrast to hypervisor technology, which carves a physical server into virtual machines (VMs), containers have been described as partitioning the underlying OS into software compartments.

The Mac OS version of Parallels Server has just left beta, and Goode expects the Windows edition to enter general availability (GA) by this fall. Interested developers and other IT pros can sign up for the Windows open beta on Parallels' Web site.

Competitors to Parallels Server such as VMware's ESX Server and Citrix's XenServer also use hypervisor technology. One big advantage of hypervisor is that other operating systems can be run on top of the underlying OS. "So if you have just one physical server, you can operate multiple OS," Goode noted.

Parallels Virtuozzo Containers, on the other hand, can be used for either Windows or Linux clusters, as Goode told BetaNews: "If you're using Windows as the underlying OS, the containers need to be Windows containers. But container technology provides really high density and high I/O, so it can be great for data center applications. With hypervisor, you're basically emulating the hardware. But with container technology, you're emulating the OS. So you don't need an abstraction layer."

HP's Intel Itanium-based Integrity servers support HP-UX, along with Windows Server 2008 and multiple flavors of Linux.

In another virtualization option for customers, though, HP is also offering embedded versions of the hypervisor-based technologies from VMware and XenServer on its ProLiant line-up of x86-based servers.