International Lattice Data Grid
Richard Kenway
University of Edinburgh
lattice QCD
 computer simulation of the strong force
– necessary to seek new physics which might
hold clues to the Theory of Everything
 national projects using Tflops computers
generating TByte data sets
– riding exponential technology curves
– towards petascale
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virtual organisation
 grand vision
– shared primary data
– shared codes
– shared machines
 reality
– Australia, Europe, Japan and US, led by UKQCD
– focus on data sharing
 grid of grids
– connect existing data repositories using web services
– provide a single public web interface
 metadata
– QCDML and data binding
– draft standard XML schema for primary data
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UK QCDgrid
QCDML
physics
history
software
LFN
physics
search
browser
Xpath
query
eXist
XML database
Tier 3
LFN
data
Edinburgh
LFN
RAL
Liverpool
“QCDOC”
data
LFN
Tier 1
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Linux PC + RAID
Globus 2.x
replica
catalogue
data
Tier 2
Swansea
ILDG via SRM
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QCDgrid operational model
 control thread
– checks disk space
available on each node
– maintains geographically
separated copies of
each file
– moves each file closest
to its point of use
– can be transferred to
another node
 replica catalogue
– tracks number and
location of file instances
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QCDML
 minimal set of XML elements for exchanging primary lattice data
– physics parameters
– QCDML glossary documents on the web for algorithm, implementation
and physics details
– extensible to other data
schema
instance document
<plaquette_gauge_action>
<plaquette_operator>
<field>link_gluon</field>
<coupling>
<beta> 5.2 </beta>
</coupling>
</plaquette_operator>
<plaquette_gauge_action>
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data format strategy
C library (provided by contributor) to
read data into standard format
contributor
format A
convert it to user's format
if necessary
standard
format
user
format B
OR
BinX description
of format A


conversion tool
BinX description
of format B
BinX is an XML schema to describe binary file format developed by the
eDIKT project
allows data binding
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a query using the metadata browser
view the XML
click get data
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grid of grids
 QCDgrid and JLab are running SRM v.1 as an interface
– SOAP based XML protocol
– JLab JAVA browser as a GUI for web services
 today
– can list QCDgrid and JLab LFNs as an aggregation of the replica
catalogues
 next steps
–
–
–
–
include Japan’s CP-PACS data
establish trust network of Certification Authorities or ILDG CA
increase functionality of the SRM
interact with the metadata
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