Speaker
Dirk Duellmann
Description
While there are differences among the LHC experiments in their views of the role of
databases and their deployment, there is relatively widespread agreement on a number
of principles:
1. Physics codes will need access to database-resident data. The need for database
access is not confined to middleware and services: physics-related data will reside
in databases.
2. Database-resident data will be distributed, and replicated. A single,
centralized database, at CERN or elsewhere, does not suffice.
3. Distributed deployment infrastructure should be open to the use of different
technologies as appropriate at the various Tier N sites.
A variety of approaches to distributed deployment have been explored in the context
of individual experiments; indeed, a degree of distributed deployment has been
integral to the computing model tests of some experiments (cf. ATLAS) in their 2004
data challenges. Approaches to replication have also been investigated in the
context of specific databases, often with vendor-specific replication tools (e.g.,
Oracle Replication via Streams for the LCG File Catalog and the Oracle
instantiation of the LCG conditions database; MySQL tools for replication in the
MySQL instantiation of the LCG conditions database). XML exchange mechanisms have
also been discussed. Distributed database deployment, though, is more than a
middleware and applications software issue—a successful strategy must involve those
who will be responsible for systems deployment and administration at LHC grid
sites.
We describe the status of ongoing work in this area, and discuss the prospects for
components of a common approach to distributed deployment in the time frame of the
2005 LHC data challenges.
Primary authors
A. Vaniachine
(ANL)
D. Duellmann
(CERN)
D. Malon
(ANL)
I. Bird
(CERN)
J. Shiers
(CERN)
M. Girone
(CERN)
M. Lamanna
(CERN)
