A. Hirstius

Native 10Gigabit Ethernet experiments over long distances

The current solutions for transmitting data over Wide Area Networks (WANs) are expensive and require protocol translation at layer 1. The IEEE recently standardized the 10Gigabit Ethernet (10GE) WAN PHY as a native gateway from the Local Area Networks (LAN) to the WAN. This opened a debate as to whether Ethernet is now a valid alternative to Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) for WANs. In this article, we report on the experience gathered while building the first trans-European native 10Gigabit Ethernet testbed based on WAN PHY. We describe and analyze network tests with a 1700km Ethernet network. Our work validates this approach and indicates that Ethernet can offer a large bandwidth to long-distance bulk data transfers at a trans-European level.

A comparison of HEP code with SPEC1 benchmarks on multi-core worker nodes

The SPEC[1] CINT benchmark has been used as a performance reference for computing in the HEP community for the past 20 years. The SPECint_base2000 (SI2K) unit of performance has been used by the major HEP experiments both in the Computing Technical Design Report for the LHC experiments and in the evaluation of the Computing Centres. At recent HEPiX[3] meetings several HEP sites have reported disagreements between actual machine performances and the scores reported by SPEC. Our group performed a detailed comparison of Simulation and Reconstruction code performances from the four LHC experiments in order to find a successor to the SI2K benchmark. We analyzed the new benchmarks from SPEC CPU2006 suite, both integer and floating point, in order to find the best agreement with the HEP code behaviour, with particular attention paid to reproducing the actual environment of HEP farm i.e., each job running independently on each core, and matching compiler, optimization, percentage of integer and floating point operations, and ease of use.

The large hadron computer

In the mid-1990s, when CERN physicists made their first cautious estimates of the amount of data that experiments at the Large Hadron Collider (LHC) would produce, the microcomputer component manufacturer Intel had just released the Pentium Pro processor. Windows was the dominant operating system, although Linux was gaining momentum. CERN had recently made the World Wide Web public, but the system was still a long way from the all-encompassing network it is today. And a single gigabyte (109 bytes) of disk space cost several hundred dollars.