Last update:
Apr 1, 2000
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The Dataflow System of the ATLAS DAQ/EF "-1" Prototype Project
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G.
et Ambrosini
al.
CERN
Speaker:
Giuseppe Mornacchi
The final design of the Data Acquisition (DAQ) and Event
Filter (EF) system for the ATLAS experiment at the LHC is scheduled to start not earlier
than 1999. Clear specification of the detector requirements, further technology
investigation of hardware and software elements and integration studies are still
required to reach maturity for the design. The ATLAS DAQ Group has chosen to approach
such pre-design investigations via a structured prototype, supporting the evaluation of
hardware and software technologies as well as their system integration aspects. A
project has been proposed and approved by the ATLAS Collaboration for the design
and implementation of a full DAQ/EF prototype, based on the Trigger/DAQ architecture
described in the ATLAS
Technical Proposal and
supporting studies of the full
system functionality, although
obviously not the required
final performance. For this
reason, it is referred to as
ATLAS DAQ Prototype "-1". The
prototype consists of a full
"vertical" slice of the ATLAS
DAQ/EF architecture, including
all the hardware and software
elements of the data flow, its
control and monitoring as well
as all the elements of a
complete DAQ system, from the
detectors Read Out Driver to
data recording. This paper
describes the dataflow
component, its design,
implementation and
performance. The architectural
view of the system and details
of its components are
described, namely: - the Front
End DAQ, consisting of the
Read Out Buffer, the local
data collection unit, the
interface to the Event Builder
and the local DAQ for the
control and monitoring - the
Event Builder, consisting of
suitable switching technology
supporting high rate parallel
data transmission - the
Sub-farm DAQ, providing data
flow support to the processor
farms running an online
implementation of the standard
ATLAS reconstruction and
physics analysis applications.
More emphasis is given to a description of the Event Builder sub-system: its
architecture, capable of running on different switching network technologies, its
implementation, based on VME SBC running LynxOS or PC's running Linux, and
performance measurements on ATM and Gigabit Ethernet technologies. The scalability
of the Event Builder, studies with simulation models, will also be presented.
The activities planned for the
use and further development of
the dataflow system will also
be highlighted.
Presentation:  | Short Paper:  |
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