April 3, 2011

With Windows Support, SGI Casts Altix UV in New Light

Michael Feldman

SGI has been getting a lot of mileage out of its SGI UV shared memory platform, having delivered close to 500 systems since it started shipping them in June 2010. Now, with the recent addition of support for Microsoft’s Windows Server, the company is looking to expand its customer base in a big way.

Altix UV, SGI’s latest generation shared-memory supercomputer, was introduced at the Supercomputing Conference in November 2009. It uses SGI’s fifth generation NUMAlink interconnect technology and Intel “Nehalem” Xeon processors to construct HPC-class SMP server nodes. The interconnect, along with the special UV hub chip, glue all the processors and memory together so that they can be operated as a monolithic resource. A fully tricked-out Altix UV 1000 will have 2,048 cores (4,096 threads via HyperThreading) and 16 TB of globally shared memory. A maximally configured machine represents 18.5 teraflops of peak performance.

Being able to command all that power within a single system image has a number of advantages, the main one being you can run standard (non-MPI) applications on a machine that for all intents and purposes behaves as an enormous PC with gobs of cores and memory at its disposal. And, by definition, such a system doesn’t require the complex set-up, software licensing, and maintenance of a distributed cluster platform — not an easy task as you approach the 1000-core realm.

Up until a few weeks ago, Altix UV came only with Linux, either Novell’s SUSE or Red Hat’s enterprise version. In early March, support was added for Microsoft Windows Server 2008 R2. The first iteration supported up to 128 cores and 1 TB of memory. On March 25, the company announced Windows Server was certified to the OS’s maximum reach: 256 cores and 2 TB of memory.

IBM and HP also have large shared memory x86-based servers with Windows Server support. But IBM’s X3950 and HP’s Proliant DL980 G7 top out at 96 and 64, respectively — well below the Windows Server limits. “Our engineering work finally brings Windows into true scalability,” says SGI CEO Mark Barrenechea.

On the other hand, Itanium-based platforms on Windows can scale to 128 cores. But with the new UV-Windows set-up, those customers (principally HP Integrity users) can now migrate their codes to SGI UV gear and achieve even greater scalability, at least on the core-count side. Itaniums still prevail in memory reach, being able to access up 128 TB.

Barrenechea says they’re targeting two major application areas with this system, the first being SGI’s traditional technical computing market. The top five application suites they expect will take advantage of the Windows-UV combo are ANSYS FLUENT, MATLAB, Mathematica, LS-Dyna, and Accelerys. These run the gamut from CFD and FEA, to computational chemistry and computational biology.

The idea here is to allow scientists to take their PC-based codes and easily slide them into these big memory UV machines with little if any porting work. In some cases, they won’t even need to perform a recompilation. A PC binary should be able to run unaltered on the Xeon-based machine (although maybe not optimally), and if the code was written correctly, will automagically take advantage of the larger memory. Of course, to utilize additional UV cores, the developer will have to parallelize the code via OpenMP threading or the equivalent.

But many of these applications are constrained only by available memory, (requiring just one to four threads to do their job). Since a typical PC isn’t going to have more than a few gigabytes of RAM, the data sizes are going to be rather limited when it comes a traditional HPC simulation code. Even a relatively modest-sized four-dimensional array of 1000 x 1000 x 1000 x 1000 byte-sized elements (for say a 3D object moving through time) will occupy an entire terabyte.

At the recent HPCC conference in Newport, Rhode Island, SGI CTO Dr. Eng Lim Goh demonstrated a simulation of the human heart developed at the University of Montreal. On a laptop, because of the limited memory, it could only be run with 60 million grid points. That delivered a rather poor resolution of the heart in action. Moving it to an Altix UV machine with 1.2 TB of memory, the model was expanded to 2 billion grid points, providing a much more realistic model.

At that scale, the simulation still took two weeks to compute a single heartbeat. Goh suggested that parallelizing the code to take advantage of the additional UV cores (768 in this case) might be able speed up the model to something close to real-time.

But big memory is not just for technical workloads. The second major application area for a Windows-capable Altix UV is on the enterprise side, in the realm of data-intensive applications. In particular, we’re talking about data warehousing, data mining, business intelligence and related types of tools. The driver behind these applications is Microsoft’s SQL Server, whose support was added in conjunction with the Windows Server OS.

This area represents a new market for SGI, although some of these customers have HPC leanings as well. In general, though, any informatics-type application that encapsulates terascale-sized structured databases is fair game for an Altix UV. The fact that many of these codes are developed in and for a Microsoft environment means there is now an easier path to greater scalability.

Barrenechea considers SGI’s entry into Microsoft’s software ecosystem a significant step for them. “Sure, we’ve supported Windows and certified it,” he says, ‘but it’s a new focus for the company.”

Of course, Linux will be the operating system of choice for most HPC users. And, in fact, Altix UV scalability is still better on that OS. Red Hat Enterprise Linux 6 reaches to 8 TB of memory, while SUSE Linux Enterprise Server 11 hits the full 16 TB. Conveniently, Linux also supports all 2,048 cores of a top-end UV, although it’s hard to imagine an SMP-based code scaled to that level.

It should be noted that the memory limit on the Altix UV is actually constrained by the current generation of Xeon chips, whose 44-bit addressing scheme maxes out at 16 TB. If your data outgrows that capacity, Intel’s next-generation “Sandy Bridge” Xeons will add a couple more bits to quadruple its memory reach to 64 TB. According to SGI’s Goh, the company plans to support the new chips in an upcoming version of the Altix UV, and already have one order for such a system.

Core counts on the next-generation Altix UV may rise as well, although the most acute demand will remain on the memory capacity side. In any case, one or more of the supported OS’s will likely be tweaked to support any new limits SGI comes up with in future UV hardware.

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