The company is changing three key features of the hypervisor technology to try to stick to its schedule of releasing the technology within 180 days of completing its Windows Server "Longhorn" operating system, due to be finalized before the end of the year. The features will be included in a future version of Viridian, formally called Windows Server Virtualization, the company said.
The first feature that is being taken out of the initial Viridian release is so-called live migration, which enables people to move a running virtual machine from one physical server to another. The initial release of Viridian also won't support on-the-fly, or "hot," adding of memory, storage, processors or network cards. And it will only support computers with a maximum of 16 processing cores--for example, eight dual-core chips or four quad-core chips.
The move limits Viridian's initial scope and gives more breathing room to competing projects--most notablyand .
"Those guys just can't get a product out the door to save their lives. Not having live migrate a year from now--talk about 'behind the times.' Windows development is just broken," Illuminata analyst Gordon Haff said. "For a (version) 1.0 virtualization offering to be missing critical features a year hence puts Microsoft in a truly bad market position, perhaps to the point where they should seriously consider partnering with VMware."
In a blog posting, the general manager of virtualization strategy at Microsoft, Mike Neil, said the company is making some "tough decisions" to meet its schedule.
"Shipping is a feature too," Neil said.
In April, Microsoftof Viridian from the first half of this year to the second half. The company said on Thursday that a public beta of Viridian will be introduced with the release to manufacturing of Longhorn Server.
"We had some really tough decisions to make," Neil said. "We adjusted the feature set of Windows Server virtualization so that we can deliver a compelling solution for core virtualization scenarios while holding true to desired timelines."
With no live migration support, Viridian will be useful for a common early use of virtualization, replacing several underutilized servers with a smaller number of more efficiently used ones. But it means that Viridian won't be immediately useful for a more sophisticated virtual-computing environment in which tasks are shuttled from computer to computer to adjust to changing work priorities or faulty hardware.
VMware, the leading x86company, has with its VMotion software. And the EMC subsidiary's Virtual Infrastructure 3 software--available for more than a year--enables much of the higher-level incarnation of virtualization that treats multiple servers as a pool of computing power.
Xen supports live migration with versions of Linux that have been specifically adapted for the virtualization software. The next version of the Xen hypervisor, 3.1, due within days, will add live migration support for Windows and unmodified Linux, said XenSource Chief Technology Officer Simon Crosby.
Capping Viridian support at 16 is a less significant change because the vast majority of x86 servers don't exceed that limit. That reality is likely to prevail, even after the second half of this year, when 16-core servers will become more common by virtue of new Intel and Advanced Micro Devices quad-core chips for servers with four processor sockets.
Being able to add new resources to servers as they run through "hot-add" capability significantly improves a server's reliability. However, it's not common for most administrators today.
Live migration can help reduce the need for hot-add technology because customers could move virtual machines to a second system while the first is upgraded or repaired.
Xen today supports hot-add capability for memory, disks, network cards and processors.