Michael Feldman ponders that question at HPCwire this week
…Optical has already notched a high-profile HPC win with the IBM Roadrunner supercomputer. That system is linked with EMCORE’s optical gear using DDR (InfiniBand) connections. According to IBM, they used over 55 miles of cable to hook all the compute and storage nodes together. For a massive system such as this, the superior physical manageability of optical fiber versus copper was probably the deciding factor.
But copper is not going down without a fight. Engineering innovation has continued to push performance to match the speeds of the latest network protocols. W. L. Gore & Associates, in particular, has been developing “active” copper cable solutions, targeting high performance interconnects for both HPC and general-purpose enterprise computing.
…According to Gore’s research, more than half of the cabling in a datacenter is less than 10 meters and the majority — maybe 90 percent — is below 20 meters. If Gore’s copper offerings are able to reach those lengths with reasonably thin cable, that doesn’t leave much of a window for optical.