February 14, 2011

Dell Unveils Eight-Socket HPC Box

Michael Feldman

Dell has introduced an ultra-dense rack server built for high performance computing. Based on the latest and greatest Opteron 6100 series (“Magny-Cours”) processors, the PowerEdge C6145 puts two independent four-socket servers in a 2U chassis, offering up to 96 cores, 1 TB memory, and 10 PCIe slots.

Since AMD introduced its 6100 Opterons last May, it has been enticing server makers to build mainstream four-socket servers with the new chips. The company’s latest-generation x86 CPU was designed to eliminate the so-called “4P tax,” a premium price associated with four-socket platforms. Although a four-socket design saves on cabling, racks and floor space, until AMD came along with its 2P-4P crossover CPU, the more complex chipsets have tended to make the four-socket servers much more expensive.

AMD has apparently made its case. All the major OEMs now have four-socket offerings based on the 6100 Opterons. But until this week, none were explicitly targeted for HPC duty.

The PowerEdge C6145 is essentially the Opteron counterpart to Dell’s Intel Xeon-based PowerEdge C6100, an HPC server that houses four two-socket nodes in a 2U chassis. The C6100 is the platform that powers the 90-teraflop “Hyperion” system at Lawrence Livermore National Lab. That system is based on quad-core Nehalem EP chips, but the C6100 is also offered with the latest six-core Westmere EP CPUs.

What the C6145 brings to the table is more x86 cores and more memory capacity in the same 2U form factor. Using the 8-core 6100 Opterons, a single server gets you to 64 cores per box; and to 96 cores with the 12-core version. Memory capacity can go up to 128 GB or 256 GB per board using 4 and 8 GB DIMMs, respectively. The upcoming 16 GB DIMMs will push this to 512 GB per board or 1 TB in the dual-node configuration.

For maximum flexibility, Dell decided to cram a lot more PCIe slots into the C6145 than it had in the C6100. In the latter case, you have just two PCIe slots (an x8 mezzanine daughtercard slot and an x16 riser slot) per node, while the new C6145 sports five (3 x16 PCI slots, an x8 mezzanine slot, and an x16 host interface card, or HIC). The idea is to be able to mix and match RAID controllers, InfiniBand cards, 10GbE NICs, and HIC devices in a very dense, core-rich server.

All the extra PCIe slottage is perfect for connecting up with Dell’s PowerEdge C410x, a PCIe expansion chassis that can be outfitted with up to 16 GPGPUs. In fact, according to Tim Carroll, Dell’s global lead of research computing, their C410x customers had a lot to do with the C6145 design.

Early users of Dell’s GPU box ended up making CPU-GPU server sandwiches with the C6100 and the C410x, but according to Carroll, what they really wanted on the CPU side was higher core counts, more memory and more PCI connectivity. The core-laden 6100 Opterons and the extra space available from a four-socket design made all this possible.

It’s worth noting a bit of irony here. The C410x is currently qualified for NVIDIA Tesla GPUs, not AMD-built ones. Nonetheless, the AMD CPUs make a perfectly respectable (and vendor-agnostic) partner to the GPGPUs.

The C6145 is not just a GPGPU driver, though. Any HPC workload that benefits from more cores, memory, and bandwidth will get a boost from the Opteron 6100. Applications in life sciences, oil and gas, computational fluid dynamics, EDA, and medical imaging should be especially favored.

This could also be an attractive platform for customers looking to consolidate their HPC infrastructure with more mundane enterprise tasks. Because of the high core count and memory capacity, the C6145 is well-suited to dense enterprise virtualization and virtual desktop infrastructure. Likewise, video rendering and transcoding could offer another sweet spot for this product.

Performance-wise, the C6145 has plenty to recommend it. Configured with the top Opteron parts, the server exhibits the highest x86 floating point throughput on the planet for an 8-socket box (based on SPECfp_rate2006 result). Prior to this, the top 8-socket record holder was the Xeon-based HP DL980 G7, a higher end offering that costs about five times as much, and at 8U, takes up four times the space.

The performance advantage can be directly attributable to the 6100 Opterons, which themselves got a speed bump on Monday. In fact, the C6145 that broke the SPECfp_rate2006 record, was outfitted with the new Opteron 6180 SE CPU, a 12-core version running at 2.5 GHz. That’s 200 MHz faster than the previous high end part, the 12-core Opteron 6176 SE. AMD also announced four other newly-accelerated 6100 CPUs: the 8-core 2.2 GHz 6132 HE and 2.6 GHz 6140, and the 12-core 1.8 GHz 6166 HE and 2.3 GHz 6176.

With the new Bulldozer architecture debuting in the upcoming “Interlagos” Opterons, an even larger speed bump is on the horizon. According to AMD, the 16-core Interlagos CPU will deliver up to 50 percent greater compute throughput and memory throughput compared to the current generation 6100 Opterons. The first such chips are scheduled to begin production in Q2, with widespread availability in Q3.

Thanks to socket compatibility, the Interlagos parts are plug compatible with the 6100s, allowing system vendors to easily transition to the new CPU architecture on the same platform. According to Carroll, the PowerEdge C6145 is due for an Interlagos upgrade when they become available. At that point, Dell will be able to offer a 128-core 2U server — something that could easily have passed for a mid-sized cluster a couple of years ago.

That’s not to say Dell will stop churning out Xeon-based gear. The Intel CPUs still reign supreme when it comes to single-threaded performance. (At 3.46 GHz, the fastest Xeon X5677 is nearly a full GHz quicker than the top end Opterons.) For HPC codes that can only scale so far, the higher clocks are the way to go.

“People spend a lot less time talking about Intel versus AMD today,” notes Carroll. “They’re really more driven by dollars per flop per watt per rack. I also think it’s going to be driven by customer requirement and use case, rather than whether it’s an AMD shop or an Intel shop.”

List price for the PowerEdge C6145 starts at $18K, with availability beginning at the end of the month. The new AMD 6100 Opteron processors are available immediately, with prices ranging from $591 to $1,514 in units of a thousand.