Speakers
Caitriana Nicholson
(University of Glasgow)
Caitriana Nicholson
(Unknown)Dr
David Malon
(ARGONNE NATIONAL LABORATORY)
Description
The ATLAS experiment will deploy an event-level metadata system as a key component of
support for data discovery, identification, selection, and retrieval in its
multi-petabyte event store. ATLAS plans to use the LCG POOL collection
infrastructure to implement this system, which must satisfy a wide range of use cases
and must be usable in a widely distributed environment. The system requires
flexibility because it is meant to be used at many processing levels by a broad
spectrum of applications, including primary reconstruction, creation of
physics-group-specific datasets, and event selection or data mining by ordinary
physicists at production and personal scales. We use to our advantage the fact that
LCG collections support file-based (specifically, ROOT TTree) and relational database
implementations. By several measures, the event-level metadata system is the
collaboration's most demanding relational database application. The ROOT trees
provide a simple mechanism to encapsulate information during collection creation, and
the relational tables provide a system for data mining and event selection over
larger data volumes. ATLAS also uses the ROOT collections as local indexes when
collocated with associated event data. Significant testing has been undertaken
during the last year to validate that ATLAS can indeed support an event-level
metadata system with a reasonable expectation of scalability. In this paper we
discuss the status of the ATLAS event-level metadata system, and related
infrastructure for collection building, extraction, and distributed replication.
Primary authors
Dr
Arthur Schaffer
(LAL ORSAY)
Dr
David Malon
(ARGONNE NATIONAL LABORATORY)
Dr
Jack Cranshaw
(ARGONNE NATIONAL LABORATORY)
Dr
Julius Hrivnac
(LAL ORSAY)
Dr
Kristo Karr
(ARGONNE NATIONAL LABORATORY)
