The Connectix Virtual Server software lets users run multiple distinct copies of server operating systems - including Windows, Linux and Unix - on a single physical machine.
The software giant recently extended standard support for Windows NT 4.0, which was due to end on 31 December 2003, by a further 12 months, but it is anxious to see users migrate to newer platforms.
However, it is unclear how receptive users will be to the latest Microsoft offering. It will not become generally available until the end of 2003, when standard support for NT4 runs out.
Connectix had promised its Virtual Server product would ship this quarter. But Jim Hebert, general manager of Microsoft's Windows server product management group, said security and code reviews, tuning and localisation work have caused Microsoft to delay the product until the fourth quarter.
Some users looking to migrate before NT4 standard support is withdrawn may well prefer to use GSX Server from Connectix rival VMware, which has been available for two years.
However, some analysts said they anticipate that many users will be more comfortable going with Microsoft's virtual machine software.
"You really want one vendor to deal with when you're dealing with operating systems," said Rob Enderle, an analyst at Giga Information Group. Enderle predicted that Microsoft would eventually build the virtual machine software into its operating system.
Microsoft's Hebert said the product might, eventually, be included with the operating system.
The benefits of virtualisation
Virtualisation software has become increasingly attractive for Microsoft users coping with the problem of Windows server sprawl, since the software can help them reduce hardware expenses and operating costs.
"We were hearing from customers that getting a supportable virtual machine solution from Microsoft would be an attractive thing," Hebert said.
NT Server users often run a single application on each of their Windows servers, either because software vendors require it or because they worry that problems with or changes to an application will cause others to crash.
Hebert noted that, as a result, much of the hardware running Windows NT Server 4.0 has gone under-utilised. But, because the hardware is nearing the end of depreciation schedules, some customers want to replace it.
Rather than moving Windows NT applications onto new hardware that will be even more under-utilised, the user can move it to faster hardware running the Virtual Server product, Hebert said. That would let several Windows NT servers be consolidated on a single box.
There is an added benefit for Microsoft. Hebert noted that the Virtual Server software requires its own underlying operating system, and Microsoft hopes customers will choose to run the Virtual Server software on Windows Server 2003, which is due out in April.