Mainz 2012 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 34: Instrumentation

HK 34.3: Talk

Wednesday, March 21, 2012, 17:30–17:45, P 2

Data Transport Challenge at ALICE HLT - Summary and Outlook — •Timo Breitner and Udo Kebschull — Institut für Informatik, Universität Frankfurt, Germany

The ALICE High Level Trigger (HLT) is used for on-line monitoring, filtering, and compression of raw detector data from the ALICE experiment at CERN LHC. A self-developed data-transport framework is used to route the incoming data stream to thousands of different processes distributed on hundreds of computing nodes. Towards the end of 2011, during the Pb-Pb beam period of LHC, we encountered the so-far biggest data challenge while running in compression mode: a large event size, combined with a high luminosity and hence event rate led to an input data rate of up 12 GB/s, and in turn to an output data rate of about 3 GB/s. Future upgrades to LHC and ALICE will lead to even bigger challenges, especially in terms of higher event rates.

The demand for a hardware upgrade at the HLT is obvious, but even more importantly the software has to be made ready for this challenge. The performance of the current software framework in past runs was therefore evaluated and the results shall be presented. Based on the experience of several years of running a new concept shall be proposed, which takes recent and expected future developments in software and hardware technologies into account.