Last week’s debut of the Intel Xeon 7500 (aka Nehalem EX) has stirred up renewed speculation about the future of Intel’s other 64-bit server chip, the Itanium. Intel launched the EX silicon with much fanfare on March 30, positioning it as a mainstream x86 processor for the mission-critical enterprise space. That message is aimed at IBM’s Power series and the Sun/Fujitsu SPARC franchise, which represent the RISC side of high-end enterprise servers. But until the Xeon 7500 came along, Intel was pushing Itanium as the slayer of enterprise RISC. That raises the question: Where does Nehalem EX leave Itanium?

Not in an enviable postion, if we are to believe industry-watchers like Charles King, principal analyst for Pund-IT. In a column this week, he writes that the Xeon 7500 will change the way system vendors and their customers think about the x86 for enterprise-class computing. From his perspective, the new processor “improves best elements of x86 computing and smooths or eliminates many, or even most, of its traditional weak spots.”

The company line from Intel on the Itaniums is that they’re still the processors for the most demanding mission-critical workloads. But the pitch is ever harder to make now that EX silicon is in the field. The new 7500 series processors close the gap with Itanium in some important areas, most notably performance and RAS (reliability, availability, serviceability). For example, the new Xeons implement Machine Check Architecture recovery, which is the same feature included in RISC and Itanium processors that enables the system to survive certain types of error conditions in a virtualized environment. Looking at the performance area, I haven’t seen any head-to-head comparisons of the new 8-core Nehalem EX and the latest quad-core “Tukwila” Itanium 9300, but I’m guessing the Xeons would outrun their more expensive 9300s on many apps.

On the other hand, the Itanium still has an edge in memory reach. An Itanium-based SGI Altix 4700 can accommodate 128 TB of RAM compared to 16 TB maximum for an EX-based Altix UV. This could be important for supersized in-memory databases on systems that are loaded with more than 16 TB of memory, although those cases would be exceedingly rare. Also, both OpenVMS and HP-UX require Itanium, so there is a bit of a captive audience there. But on balance, the Itanium is being edged out by its more popular x86 sibling.

This is probably most true in the HPC arena, which has likely seen its last Itanium supercomputing platform in SGI’s Altix 4700. As of today, there’s no public roadmap for a 4700 follow-up, although the company is still cheerleading for the CPU. As recently as July 2009, SGI CEO Mark Barrenechea posted in his blog that the company was “100 percent committed to Itanium.” But it’s certainly no coincidence that the first (and so far, only) implementation of SGI shared memory Altix UV is on Nehalem EX. When Intel finally released Tukwila parts in February 2010, SGI was conspicuously silent.

We may yet see an Itanium-based Altix UV if SGI can find a rich customer or two that loves the CPU enough make the system development and support worthwhile. However, since most HPC users are hooked on Linux and use C or Fortran as the development language, there’s no particular dependency on the underlying silicon. As long as the apps don’t need the extended memory afforded by Itanium servers, the software should migrate relatively painlessly to 64-bit x86.

Yet more bad news is that OS vendors are bailing. Both Red Hat and Microsoft are phasing out support for Linux and Windows, respectively. Red Hat announced its plans to drop Itanium support for Enterprise Linux 6 back in December 2009, while Microsoft recently revealed its intent to terminate support after Windows Server 2008 R2. That basically leaves HP-UX, Hewlett Packard’s own flavor of Unix, as the go-to OS for Itanium. Frankly, that was always the case. Linux and Windows represent a relatively small piece of the market on this platform.

In fact, HP has always been the major vendor of Itanium big iron, with its Integrity server line. There are even a handful of Integrity machines in the HPC world, and the Spanish seem particularly fond of them. The Lusitania super at the Extremeño Center for Research, Technological Innovation and Supercomputing consists of two Integrity Superdomes that aggregate 256 Itanium2 processor cores and 2 TB of RAM. The Finisterrae supercomputer is a 144-node Integrity cluster that contains 2,580 Itanium processors and 20 TB memory. All of the other HPC Itanium-based machines are Bull SMP NovaScale systems, and of course, the aforementioned SGI Altix 4700s.

Bull, SGI and HP have already hopped on the Nehalem EX bandwagon. As we reported last week, Bull and SGI are employing the new EX silicon to build their SMP HPC offerings. HP also has plans for Nehalem EX, although as the Register’s Timothy Prickett Morgan noted, the company has kept its specific EX offerings under wraps for the time being. Certainly, HP must be of two minds regarding the new Xeons, given that there’s no longer much daylight between Nehalem EX and Tukwila, capability-wise. Presumably HP already has a plan to migrate its Integrity customers onto future x86 platforms. The only other alternative would be to acquire the Itanium franchise from Intel before the x86 chipmaker loses interest completely.

When Intel decides to drop Itanium is anyone’s guess. Officially, the company still has two future implementations on the roadmap. Poulson, tentatively planned for 2012, is a 32nm Itanium with more cores (at least 8), multithreading enhancements, and additional instructions. After that comes Kittson, which is due out in 2014. Since Intel has been consistently tardy on its Itanium releases, those dates could slip substantially. Or Intel could pull the plug sooner if its success with the Nehalem EX and the future Westmere EX shrinks the demand for Itanium business beyond redemption. What is certain is that Intel has already made the calculation that it wouldn’t let Itanium dictate how it moves forward with its x86 architecture.