August 26, 2014

Cray Adds GPU Powerhouse to CS Supercomputer Lot

Nicole Hemsoth

The CS family of Cray systems was graced with a new addition today with the arrival of a dense, memory-loaded GPU offering that adds big acceleration to select HPC workloads.

The new CS-Storm, which offers up to 8 NVIDIA K40s per 2U server and a peak performance of 11 teraflops per Ivy Bridge-outfitted node, is set to push key applications that require more GPU scalability to new heights.

The system, which is based on the Cray CS300 super, is designed to keep the accelerators cool enough to operate at full speed. The 48U standard rack can accommodate 22 of the 2U nodes, which means that with 2 Ivy Bridges and the GPUs, users are looking at around 250 teraflops per rack or a petaflop of performance for a 4-cabinet purchase. Cray’s Barry Bolding told us that the company will release more information on future Intel generations for the host processor.

It’s not just about adding GPUs into the dense mix with this system, however. Cray has tuned the GPU workloads they’re targeting for maximum bandwidth and accelerator performance on the cooling and data movement fronts with a couple of notable features.

While these are air-cooled systems, as the graphic below shows, the emphasis is on cooling through front to back airflow to keep the GPUs humming without overheating or without having to run them at reduced wattage. In addition to airflow, this allows for expandability options since it will be possible to add future generations of accelerators into the box while still allowing the desired density and the ability to cool all 8 of the GPUs at the same time.



As you can see, these are also outfitted with more memory than the CS systems and features bandwidth-maximizing for these applications via the centered mothered with 2 CPUs and 4 GPUs on either side of the 2U configuration. Again, this aids in cooling and expandability but also note how they are running the PCI off each side of both sockets, which means they can run these through a PCI switch and split the PCI Gen 3s into 8s to run them at full bandwidth. While this isn’t a novel design necessarily, for the purposes of a system like this, it’s required.


“We’ve seen a number of customer requirements in the energy, high frequency trading, and government sectors as well as for a number of different use cases,” said Bolding. He pointed to other areas that are feeding demand for high-density GPU systems, including machine learning, seismic processing, and image processing.

Although pressed for a sense of pricing on the new CS-Storm supercomputer system, Bolding merely said that these are in early manufacturing and production and will be available for limited shipping immediately with volume shipping in Q4 of this year. He said that when compared to their CS system line in general, the GPUs will add to the cost of any configuration—meaning these are likely about the same cost of the air-cooled CS line, with the addition of the GPUs since aside from this addition and some of the software additions (OpenACC support and other GPU-based features) there isn’t a lot of custom engineering cooked in.

On that note, Cray is using essentially the same software environment one would expect with a CS300, but there are libraries that are GPU accelerated with adapted runtimes that will allow for GPU acceleration. While it’s not shown, as one would expect, they are carrying compilers that are OpenACC optimized and also supporting the expected Intel and NVIDIA software required for running accelerated workloads.

When Cray sets about designing a new product for a larger set of users, the company evaluates demand potential based on customer conversations and market data. Bolding says this is not a one-customer or custom designed product and that GPUs are a mature offering that is pushing customers to look to larger, more powerful accelerated systems now that they’ve had success with adding GPU nodes and tuning their applications.

“The CS family is a market-driven one, but it’s flexible, which means we can quickly design new form factor boards and server units. What we’ve seen is a growing demand for 8 GPUs and internally, we ran a business case on how big we think that market is see if it justified the development of a new offering,” said Bolding.

“This one was relatively new as a design,” he continued, “it was not in our portfolio before but we thought we could combine the hardware and software better than the competition.”

“Adding a GPU-dense, air-cooled option to the already-extensive lineup of Cray’s CS300 offerings will further expand the market for this standards-based cluster supercomputer product,” said Steve Conway, IDC research vice president for high performance computing. “IDC research showed that the proportion of sites employing accelerators and other coprocessors in their HPC systems jumped from 28.2 percent in 2011 to 76.9 percent in 2013, and GPUs are the clear leaders in this category. Cray has been on a roll, and ramped-up sales of its Cray CS300 line have helped.”


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