Server OEMs put Intel's Itanium in hot seat
By Jerry Ascierto and Mike Clendenin
EE Times
(08/09/01 19:34 p.m. EST)
CUPERTINO, Calif. — Intel Corp.'s effort to drive its Itanium microprocessors into more muscular servers is clashing with system engineers' desire to build compact servers for tomorrow's Internet data centers, a class of machine for which the Intel CPUs are too hot. Intel may not fully be able to address the power-dissipation problem until it rolls out 0.1-micron process technology in 2004, one analyst said.
"If you're thinking about layers of computing in the data center, you say ,'Do I really need the front end to have the [performance] of McKinley [Intel's next-generation Itanium chip] — and the answer is probably not," said Ali Ezzet, senior system architect for Hewlett-Packard Co.'s Network Server Division. "It's more important for me to have the density, so what I really care about is getting down to half the power."
Ezzet is just one of many server engineers pressuring Intel to cut the exceptionally high heat dissipation of the Itanium processors, the first generation of its new IA-64 CPU line. Intel's most effective tool in reducing the power budget — namely, shrinking the die to 0.13-micron design rules — is still at least a year away.
At 130 watts, the 0.18-micron Itanium dissipates significantly more heat than the 32-bit Pentium 4. "If you open up our [Dell PowerEdge] 7150 [a 7U server with four Itaniums], about two-thirds of that is fans," said Kevin Libert, director of Dell Computer Corp.'s Enterprise Systems Group. That's typical of many Itanium servers, said Libert, who maintained that the problem will persist with the 0.13-micron versions of Itanium.
Indeed, heat dissipation has become such a concern that some system designers say Intel may have to partially cripple performance to meet power budgets. This is one option that engineers like Ezzet expect Intel to play.
"Do we really need 100 percent performance in McKinley and the follow-ons, or can we live with something a little bit less?" Ezzet said. "It might be something that's 90 percent the performance but 30 percent of the power."
Intel has labored for years to outperform competing reduced-instruction-set computing processors such as Sun Microsystems' Sparc, Compaq's Alpha and HP's PA-RISC. But just as Intel has staked out a leadership position in chip performance, system design has downshifted from large monolithic machines that ran the internal applications of thousands of users in big companies, to dense rack-mounted units that put as many processors as possible on a single board and as many boards as possible in a rack to run Web apps for millions of users.
Many small transactions
As Internet data centers continue to drive server density, often that density takes priority over the individual performance of each CPU. Such computing resources engage in many small transactions, like content delivery, where small amounts of content are distributed in parallel and hits compile in the blink of an eye.
Thus, even as the Santa Clara, Calif., CPU giant peppers the mass media with a "microprocessing/macroprocessing" ad campaign that pushes its image as a high-octane component maker, engineers are privately clamoring for an approach that puts power consumption over raw performance.
Competitors such as Sun, meanwhile, will be looking to take advantage of Intel's power problems. The latest spin of Sun's 64-bit Ultrasparc 3, which has been moved to a new 0.15-micron, all-copper process technology, will tout power dissipation of 75 W, some 42 percent lower than Itanium.
So far, Intel has not said whether it will come out with a low-power version of Itanium. "Our goal is to have Deerfield [a version of the Itanium architecture planned for release in late 2002, early 2003] be a product that will broaden the range of solutions, and take in more price/performance platforms," said Shannon Poulin, a manager for the Itanium product line at Intel. "Itanium is at the top end of our road map now, but we expect that to waterfall down into some of the smaller form factors, like the 2U [size] boxes, over time." Moreover, he said, "we expect [Pentium 4 and Itanium server] products to coexist for quite some time."
Still, analysts and engineers think low-power Itaniums are inevitable. "At some point in time Intel might have a high-power and a low-power Itanium part, the same way they have higher-power versions of the Pentium III," said Linley Gwennap, president of market research firm The Linley Group (Mountain View, Calif.).
"The big issue with Itanium is that you're doing a lot of speculative execution," said Gwennap. "If you're executing something speculatively a lot of times, often you don't need it, so it may be wasted power. So Intel can dial down the speculation and you get a trade-off, obviously." Still, doing less speculation "is going to reduce performance, but not by much," Gwennap said.
The Intel processor code-named Madison will be a high-performance 0.13-micron part, while Deerfield looks to be a lower-end device. "With Deerfield, Intel will try to reduce power to fit it into these dense servers, but it may take until the 0.1-micron process generation to really get Itanium into dense servers," said Kevin Krewell, server analyst for MicroDesign Resources (San Jose, Calif.). "I don't expect Itanium to go into dense servers until around 2004."
OEMs respond
Intel claims Itanium is ready for dense server designs today. "We've done some basic studies that show you can take Itanium into these dense form factors with standard cooling techniques," Poulin said. "But certainly there may be some trade-offs you make in the way you configure the system and get air in and out of the box."
OEMs have a more mixed view. "It's very possible that we'll have to break from conventional cooling methods at some point," said Tom Bradicich, director of architecture and technology for IBM Corp.'s eServer xSeries. "Our research labs are currently doing a lot of work in that area. Right now, we push the conventional cooling limit."
At IBM, "We plan to offer from a four-way-scalable up to a 16-way system," said Bradicich. "We're able to refine our thermal-management architecture; so we're taking a conventional technology, with blowers and fans, and innovating on top of that, with ways of managing airflow" that leverage IBM's work in mainframe and minicomputer design, he added.
Dell's Libert believes that a low-power Itanium line would first find its way into workstations, not servers, mainly due to the higher unit volumes found in that segment. "With workstations, rendering graphics with 64-bit [technology] is so much more spectacular, so there's an immediate payoff, and you've got the volume model," he said.
Libert said Dell doesn't expect its 7150 server "to blow the doors off in terms of volume right now." He said the company would use the initial Itanium chip more for development work.
Thus, "Workstations may lend themselves to the volumes and the need for a lower- and higher-end line," he said, and the pressure on Intel to do a low-power line of Itaniums "is going to come from the workstation area first. There's tons of pressure there."
Even the current Pentium III and next-generation Xeon chips are too hot, according to Ares Chen, product manager at Nexcom, a Taiwanese designer of servers. "The thermal issue is the first concern for our product designs," Chen said. "For many of our servers, it's difficult to put the Pentium III 1-GHz solution into a 1U chassis. That's the reason many designers try to put in up to four or five fans, and maybe even a blower."
In Chen's view, new packaging techniques may be an answer. "In traditional socket designs, for the Pentium III or Pentium 4 and even the Xeon, the power consumption is very high," Chen said. "But with BGA packaging or microBGA packaging, the power consumption is only half or a third of the socket solution."
The trade-off is a downgraded CPU performance, he said, and the same holds true for low-power versions of the Xeon. "In the next-generation Xeon, the maximized speed is 2.5 GHz or 3 GHz, but for the low-power-consumption version, the clock rate starts from 1.6 GHz," said Chen. "It's not a happy trade-off, but it's the only solution right now."
Like Dell and IBM, Compaq Computer Corp. is shipping 7U boxes containing four initial Itanium chips. Compaq's ProLiant DL590/64 is its first offering in a planned Itanium line. "We will go to denser form factors. Typically, we try and overengineer if possible, and add more cooling capabilities," said Steve Comings, a senior product manager in the enterprise server group.
Heat pipes
Future offerings might follow the lead of the ProLiant 8500's cooling method, which makes heavy use of heat pipes, said Curt Belusar, an engineering program manager at Compaq.
Intel recently rolled out the 0.13-micron Tualatin, a Pentium III chip aimed at both the mobile and entry-level server arenas. A beefed-up Level 2 cache — doubled to 512 kbytes over previous Pentium III offerings — makes the dual-processor version of the chip attractive for servers.
The high-performance Xeon line, already at 1.7 GHz, will be bumped to better than 2 GHz by yearend, Intel's Poulin said, but won't move to 0.13-micron process technology until the first half of 2002. "A four- and eight-way version, the Xeon MP, is expected to appear in the first half of next year," Poulin said.
Intel is expected to keep its current Itanium and follow-on McKinley on its older but more stable 0.18-micron technology. Intel's most advanced 0.13-micron process is now only found in its Pentium III processors.
After McKinley, "The next versions of Itanium will migrate to 0.13 micron," said Krewell, the MicroDesign Resources analyst. "That should lower power, but it will still be a challenge" for the system OEM designing dense servers, he said.
Additional reporting by Anthony Cataldo. |
