Speaker
Mr
Ulrich Fuchs
(CERN & Ludwig-Maximilians-Universitat Munchen)
Description
ALICE is a dedicated heavy-ion detector to exploit the physics potential of
nucleus-nucleus (lead-lead) interactions at LHC energies. The aim is to study
the physics of strongly interacting matter at extreme energy densities, where
the formation of a new phase of matter, the quark-gluon plasma, is expected.
Running in heavy-ion mode the data rate from event building to permanent
storage is expected to be around 1.25 GB/s. To continue data recording even in
the event of hardware failure or connection problems, a large disk pool has
been installed at the experiment's site as buffering layer between the DAQ and
the remote (~5km) tape facility in the CERN Computing Centre. This Transient
Data Storage (TDS) disk pool has to provide the bandwidth to be able to
simultaneously absorb data from the event building machines and to move data
to the tape facility. The aggregated bandwidth of the TDS is expected to exceed
3 GB/s in mixed I/O traffic.
Extensive tests have been carried out on various hardware and software
solutions with the goal to build a common file space shared by ~60 clients,
whilst still providing maximum bandwidth per client (~400MB/s, 4Gbps Fibre
Channel), fail-over safety and redundancy.
This talk will present the chosen hardware and software solution, the
configuration of the TDS pool and the various modes of operation in the ALICE
DAQ framework. It will also present the results of the performance tests carried
out during the last ALICE Data Challenge.
Primary author
Mr
Ulrich Fuchs
(CERN & Ludwig-Maximilians-Universitat Munchen)
Co-authors
Csaba Soós
(CERN)
Franco Carena
(CERN)
Irina Makhlyueva
(CERN)
Klaus Schossmaier
(CERN)
Pierre Vande Vyvre
(CERN)
Roberto Divià
(CERN)
Mr
Sylvain Chapeland
(CERN)
Wisla Carena
(CERN)
