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Turning server communication inside out

Sun bets customers will reward it for technology called ExpressModule, which moves PCI outside the computer.

Sun Microsystems and a handful of computing companies have taken crucial first steps in delivering to the world a flexible new way to plug network cards and other adapters into servers.

The technology, called PCI ExpressModule, is an extroverted version of the ubiquitous PCI (Peripheral Component Interconnect) standard that until now has been hidden away inside computer cases. Traditional PCI cards are naked electronics boards that fit into slots inside a computer's chassis, but PCI ExpressModule uses cartridges that slide into external slots.

The technology promises to ease the lives of server administrators who need to add or replace cards without opening up the computer, removing it from its rack or shutting it down. ExpressModule adapters cost more, though, and their advantages are likely to have little appeal for those using lower-end servers.

If Sun has bet correctly, it will have desirable products on the market ahead of rivals and could restore some of its reputation as a "hot box" manufacturer. But if not, it could be punished for foisting more expensive technology on its customers.

"Sun is probably betting that the ecosystem is going to create itself and that Sun will be there early to take advantage of some of the unique capabilities," said Ideas International analyst Rich Partridge. But it's always difficult to turn new input-output standards into mainstream technology: "It's a hard, steep curve to climb up."

And Sun won't have any help, at least for now, from the other two major manufacturers of higher-end servers, IBM and Hewlett-Packard.

ExpressModule "hasn't had much adoption in the industry," so IBM is still only evaluating the technology, said Jeff Benck, vice president of product development for IBM's x86 and blade servers.

And HP won't use it in its x86-based ProLiant servers and has no imminent plans for its higher-end Itanium-based Integrity models.

"At this point, the reliability, availability, serviceability, manageability and density of ExpressModule do not demonstrate sufficient benefits beyond the standard PCI-Express form factor, which offers lower cost and wider product selection," said Brian Cox, worldwide director of server platform marketing for HP's business critical server group, in a statement.

But Sun expects minds to change. "I think it's going to take another year before we see (usage) go up dramatically," said Graham Lovell, senior director of systems at Sun. "I think it's going to go mainstream in the big four suppliers"--meaning IBM, HP, Dell and Sun--he said.

The chicken-and-egg problem
Input-output standards move glacially compared to the rest of the computer market, and the work in building support for ExpressModule has only begun. The ExpressModule debut is a classic example of the who-goes-first, "chicken-and-egg" problem that's common with new technology introductions.

"You need the platform to develop the cards, but the platform needs the cards. It's going to take a little bit of getting there," said Al Yanes, chairman of the PCI Special Interest Group (SIG) that oversees all PCI specifications.

But Yanes is optimistic that Sun's move will help the ExpressModule fortunes. "Sun's a big player. Hopefully that's going to jump-start the technology," he said. "We're hopeful that others will endorse it."

The PCI SIG released the ExpressModule specification in April 2005, scrapping the former Server I/O Module name.

But PCI ExpressModule didn't become a practical reality until July 2006, when Sun announced its Sun Blade 8000 server, one of several designs led by respected computer engineer Andy Bechtolsheim.

There are some adapter eggs to go along with the server chicken, Lovell said: Qlogic and Emulex will supply dual-port Fibre Channel adapters; Intel plans two- and four-port gigabit Ethernet adapters; Mellanox plans dual-port InfiniBand network adapters; and Myricom "and others" plan dual-port 10-gigibit Ethernet adapters.

Now that Sun has staked its claim, "We're hoping that it's going to catch the attention of the other server vendors. "It's a great feature on midrange servers and up," said Frank Berry, vice president of marketing for QLogic, which offers dual-port adapters for connecting servers to Fibre Channel storage networks.

New circuit boards must be designed for ExpressModule, Berry said, but the main engineering--the custom processors, software drivers and on-board firmware--is the same. "All that's portable to the new design," he said.

Adaptec, a major manufacturer of adapters for connecting to storage systems, doesn't have ExpressModule models. But it's a fan nonetheless. "We do like the technology. We looked at it as a way to add cards to a server without having to bring the server down. Anything that increases the uptime for servers we're supportive of," said Paul Vogt, director of product marketing.

Conventional PCI has technically permitted customers to add or change cards while a server is running--"hot-add" and "hot-swap" in server jargon--but in reality the idea is too impractical. "There were huge concerns about that--about the danger of having the machine on while taking the cover off," Vogt said.

Mass market?
Few doubt ExpressModule has benefits in higher-end servers, whose lifespans last many generations of upgrades and which customers are more reluctant to shut down. But the mainstream market is another question.

Sun is bullish on the idea, though its lower-end products don't use it, at least for now. Lovell expects PCI ExpressModule to be used in dual-processor, rack-mounted machines as small as 3.5 inches thick--the single most popular area of the server market in terms of unit shipments.

But HP, the top maker of x86 servers, will take some convincing.

The industry effectively voted against ExpressModule as the PCI standard plug-in method when it decided how to move from conventional PCI to the faster PCI-Express (PCIe) technology now becoming mainstream, said Dwight Barron, chief technologist for HP's BladeSystem.

"If the industry was going to move to this modular format, the time to have done it was when we made the transition to PCI Express. The industry voted loud and clear. PCIe happened, and we're on the same kind of cards we've been on for a long time," Barron said.

The computing industry is several years into its transition from PCI to PCI-Express, a new version that offers faster connections through high-speed "serial" communications lines rather than the synchronized "parallel" links used in older PCI. While servers today still often use an extension to PCI called PCI-X, lower-end servers have begun the transition to PCI Express.

The ExpressModule is "a relatively a niche product," and HP doesn't have plans to use it in its ProLiant servers, Barron said.

And that lukewarm stance ultimately could mean ExpressModule fans won't see their products coast to easy widespread acceptance. "If HP and IBM don't make use of this, I'm not sure it withers on the vine," said Illuminata analyst Gordon Haff, "but it certainly is a much smaller market than regular PCI-Express cards."