Author :
Vermeulen, J. ; Abolins, M. ; Alexandrav, I. ; Amorim, A. ; Dos Anjos, A. ; Badescu, E. ; Barros, N. ; Beck, H.P. ; Blair, R. ; Burckhart-Chromek, D. ; Caprini, M. ; Ciobotaru, M. ; Corso-Radu, A. ; Cranfield, R. ; Crone, G. ; Dawson, J. ; Dobinson, R. ;
Abstract :
In the ATLAS experiment at the LHC, the output of readout hardware specific to each subdetector will be transmitted to buffers, located on custom made PCI cards ("ROBINs"). The data consist of fragments of events accepted by the first-level trigger at a maximum rate of 100 kHz. Groups of four ROBINs will be hosted in about 150 read-out subsystem (ROS) PCs. Event data are forwarded on request via Gigabit Ethernet links and switches to the second-level trigger or to the event builder. In this paper a discussion of the functionality and real-time properties of the ROS is combined with a presentation of measurement and modeling results for a testbed with a size of about 20% of the final DAQ system. Experimental results on strategies for optimizing the system performance, such as utilization of different network architectures and network transfer protocols, are presented for the testbed, together with extrapolations to the full system
Keywords :
data acquisition; high energy physics instrumentation computing; local area networks; particle accelerators; particle detectors; readout electronics; transport protocols; ATLAS DataFlow; DAQ system; Gigabit Ethernet links; LHC; PCI cards; data acquisition system; network architectures; network transfer protocols; readout hardware; readout subsystem; real time systems; Data acquisition; Ethernet networks; Hardware; Large Hadron Collider; Personal communication networks; Real time systems; Size measurement; Switches; System performance; System testing;
