World's 1st SSD-based super computer?
The university made two major improvements for enhancing the performance of the system. First, it improved the memory bandwidth. Specifically the network bisection bandwidth (the minimum communication capacity of the cross section at a random part of the system) is about 200 Tbps, which is 33 times higher than that of the Tsubame 1.0, a supercomputer system constructed by the university in 2006.
Moreover, the total memory bandwidth is 720 Tbps, which is about 42 times higher than that of the Tsubame 1.0. And the computation capacity was increased by about 30 times.
The other improvement was made to the memory and its composition. The university structured a multilevel storage using not only DRAMs such as DDR3 but also SSDs (solid state drives) composed of flash memories.
While the total memory capacity of the backbone system's DRAMs is 80.6 Tbytes for microprocessors and 12.7 Tbytes for GPUs, the total memory capacity of the SSDs is 173.9 Tbytes. SSDs have a high performance in inputting and outputting data.
"By using them to input and output local data (that are not shared by other nodes), the performance of the entire system can be enhanced," Matsuoka said.
Sharp decrease in power consumption
The new supercomputer system has one more noteworthy feature: low power consumption. While the power consumption of the Tsubame 1.0 including its cooling system is 0.85MW, that of the Tsubame 2.0, which has a 30 time higher computation capacity, is only 1MW. So, the power consumption per computation capacity was reduced to about 1/25.
The performance value per watt (in terms of the Linpack benchmark) is expected to exceed 1,000 MFLOPS (megaflops) per watt and will possibly be ranked first in the Green500, a ranking of supercomputer's energy saving performance, the university said.
"We not only used a large number of GPUs but also drastically enhanced the efficiency of the part around the power supply from 80% to 94% and employed a sealed cooling system," Matsuoka said.
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