IDG News Service — VMware customers are getting a bit more freedom in the way they can transfer virtual machines from one Intel-based server to another, but they shouldn't hold their breath waiting for a bridge between Intel and AMD-based systems, an Intel executive said Tuesday.

With its line of Xeon 7400 processors released this week, Intel is enabling customers using VMware's vMotion technology to move virtual machines between two servers even when they are based on different families of Intel chips.

VMotion is VMware's technology for moving running virtual machines onto a different physical server. It's used by some customers for load balancing or for building fault tolerance into applications.

Before the 7400 series, also known as Dunnington, the two servers had to use the same family of Intel chips for vMotion to work, said Doug Fisher, vice president with Intel's Software Solutions group, at the VMworld conference in Las Vegas. With the 7400 and future chip families, that restriction is lifted.

VMware CEO Paul Maritz mentioned the development in his speech at the start of VMworld Tuesday. "Now you'll be able to buy hardware essentially independent of your vMotion strategy," he said.

The compatibility goes back only to the previous processor family, the 7300 "Tigerton" series, and will extend to the next generation, known as Nehalem. "We'll always give at least three generations of compatibility," Fisher said.

Intel made a big deal about the news, but AMD said its Opteron processors have had a similar capability for years. AMD doesn't change the microarchitecture of its processors as frequently as Intel, so compatibility between different Opteron lines is not an issue, said Margaret Lewis, AMD director of commercial solutions.

Customers looking to move virtual workloads between AMD- and Intel-based servers are out of luck, however, at least for the foreseeable future, according to Fisher.

"It's not going to happen," he said on the sidelines after his speech. The companies' chip architectures, while both x86, are too different and change too frequently to be made compatible. "We'd have to slow the pace of innovation to make it happen," he said.

Lewis suggested it was only Intel, not AMD, that changes its architecture frequently. "We'd need to sit down with Intel and VMware and discuss how to make it happen, and we would welcome that discussion," she said.

AMD would stand to gain the most from such compatibility, since it would give companies one less reason to buy Intel-based servers.

Dunnington is a six-core processor with a larger, 16M byte Level 3 cache to boost performance. VMware CTO Steve Herrod said VMware will keep its per-socket pricing the same for Dunnington, "so customers can get more virtual machines per processor" without paying more in licenses.

It was one of several ways Fisher said Intel is working with silicon to usher in a "second wave" of virtualization. The first wave was using the technology for server consolidation and building virtual environments for software testing, and the second is to use it for load balancing, high availability and disaster recovery.

Citing IDC figures, he said that in 2007 about 12 percent of all servers in production were using virtualization, up from 8 percent in 2006 and 4 percent the year before. Virtualized servers run at 52 percent capacity on average, he said, compared to 10 percent to 15 percent for non-virtualized systems.