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Jean-Yves Nief, CC-IN2P3

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BaBar data distribution using the Storage Resource Broker (SRB) Jean-Yves Nief, CC-IN2P3 Wilko Kroeger, SCCS/SLAC Adil Hasan, CCLRC/RAL HEPiX, SLAC – PowerPoint PPT presentation

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Title: Jean-Yves Nief, CC-IN2P3


1
BaBar data distribution using the Storage
Resource Broker (SRB)
Jean-Yves Nief, CC-IN2P3 Wilko Kroeger,
SCCS/SLAC Adil Hasan, CCLRC/RAL
HEPiX, SLAC October 11th 13th, 2005
2
BaBar overview.
  • Large amount of data produced by BaBar gt 800 TB.
  • Using the collaboration Computing Centres
  • Data (re)processing (prompt reco, skimming).
  • Simulation production.
  • Data analysis ? allow foreign collaborators to
    access data.
  • 6 Tier A
  • SLAC stores all the data simulation central
    repository.
  • Computing tasks divided among all the Tier A
    sites.

3
BaBar data organization.
SLAC CC-IN2P3 Padova RAL CNAF GridKa
Data processing
Data analysis
simulation production (20 sites involved)
? Lots of data movement
4
Requirements.
  • Short turn-around between data production and
    analysis.
  • Data must be transfered efficiently and quickly
    to Computing Centres.
  • Data transfer tools must be
  • Reliable.
  • Robust.
  • Automated.
  • Scalable.
  • Easy to use.

5
SLAC CC-IN2P3.
  • First analysis centres opened to the BaBar
    collaboration.
  • Both held complete copies of data (Objectivity).
  • Now only SLAC old a complete copy of the data.
  • Natural candidates for testing and deployment of
    grid middleware.
  • SRB good candidate for data distribution.

6
Whats SRB ?
  • Storage Resource Broker developed by SDSC (San
    Diego).
  • Provides an uniform interface to heterogeneous
    storage system (disk, tape, databases) for data
    distributed in multiple sites.
  • Who is using SRB ?
  • Biology, biomedical applications (e.g BIRN).
  • Astrophysics, Earth Sciences (e.g NASA).
  • Digital libraries (e.g NARA).
  • Used world wide USA, Europe, Asia, Australia.

7
Some SRB features.
  • Files organized in a logical space (directories,
    subdirectories ) logical view totally decoupled
    from the physical location of the files.
  • Replica management.
  • Search for files based on their attributes
    (metadata).
  • Fine granularity for SRB usersACLs.
  • Interfaced with various Mass Storage System
  • Access to HPSS transparent to users.
  • Small files management.
  • And many more

8
SRB architecture.
  • 1 zone
  • 1 SRB/MetaCatalog server contains list of files,
    physical resources, users registered.
  • several SRB servers to access the data at their
    physical location.

(3)
Site 1
test1.txt
Application (asking for test1.txt)
9
SRB BaBar architecture (2001-2004).
1 Zone (SLAC)
client
CC-IN2P3 (Lyon)
SLAC (Stanford, CA)
10
Extra details.
  • Hardware
  • SUN servers (Solaris 5.8, 5.9) NetraT 1405,
    V440.
  • Software
  • Oracle 8, 9 for the SLAC MCAT (530,000 files
    registered).
  • Multithreaded client application (Python).
  • Advantages
  • All the 3 steps controlled by the client
    application in // ? no latency due to prestaging.
  • Small amount of cache needed on both sides (a few
    GBs).
  • Drawbacks
  • No registration into the MCAT of the files stored
    in Lyon.
  • Performance
  • Up to 3 TB/day from tape to tape.

11
ESNET Traffic with one server on both sides
(April 2004).
SLAC (US) ? IN2P3 (FR)
1 Terabyte/day
Fermilab (US) ? CERN
SLAC (US) ? INFN Padva (IT)
Fermilab (US) ? U. Chicago (US)
U. Toronto (CA) ? Fermilab (US)
Helmholtz-Karlsruhe (DE)? SLAC (US)
CEBAF (US) ? IN2P3 (FR)
INFN Padva (IT) ? SLAC (US)
Fermilab (US) ? JANET (UK)
SLAC (US) ? JANET (UK)
DOE Lab ? DOE Lab
Argonne (US) ? Level3 (US)
DOE Lab ? DOE Lab
Fermilab (US) ? INFN Padva (IT)
Argonne ? SURFnet (NL)
IN2P3 (FR) ? SLAC (US)
12
SRB BaBar architecture (since 2005).
2 Zones (SLAC Lyon)
SRB
CC-IN2P3 (Lyon)
SLAC (Stanford, CA)
13
Extra details.
  • Hardware
  • Still the same.
  • Software
  • Oracle 10g for the SLAC MCAT.
  • Oracle 9i for the Lyon MCAT (migration to 10g
    foreseen).
  • MCATs synchronization only users and physical
    resources.
  • Comparison of the MCATs contents to transfer the
    data.
  • Advantage
  • External client can pick up data from SLAC or
    Lyon without interacting with the other site.

14
Overall assessment.
  • A lot of time saved for developping applications
    thanks to the SRB.
  • Transparent access to data
  • Very useful in an hybrid environment (disk,
    tape).
  • Easy to scale the service (adding new servers).
  • Not dependent of physical locations changes in
    the application.
  • Fully automated procedure.
  • Easy for SLAC to recover corrupted data.
  • 132 TB (232,000 files) shipped to Lyon.
  • Up to 3 TB /day from tape to tape (minimum
    latency).

15
Future plans.
  • Possibly include RAL as part of the system
  • Would reduce the network activity on the SLAC
    ESNET.
  • Some tests
  • Assessment of web services technologies.

16
Summary and outlook.
  • SRB used by BaBar for more than 3 years.
  • Data shipment fully automated.
  • Lightweight development to make it work.
  • Easy administration.
  • More servers on both side
  • Increase peak transfer rate to 5 TB/day.
  • Hundreds of TB foreseen.
  • Scalability the sky is the limit well and the
    money too
  • Aiming at including RAL.

17
Never forget
  • Cannot be achieved without the work of
  • The network and system admins.
  • The database admins.
  • Many thanks to them!
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