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New KanGA Export Scheme. Tim Adye Rutherford Appleton Laboratory BaBar Collaboration Meeting Data Distribution Session 13 th December 2000. ftp TNG Selecting events for export Running the export procedure. Optimising ftp throughput.

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New kanga export scheme

New KanGA Export Scheme

Tim Adye

Rutherford Appleton Laboratory

BaBar Collaboration Meeting

Data Distribution Session

13th December 2000

Tim Adye

New kanga export scheme

  • ftp TNG

  • Selecting events for export

  • Running the export procedure

Tim Adye

Optimising ftp throughput
Optimising ftp throughput

  • ftp / scp / rsync(syncslac) are not optimised for bulk transfers over the WAN

  • Optimisations possible

    • Use multiple-streams

      • Separate processes/threads copy different parts of the data

    • Adjust TCP/IP parameters

      • Large improvements from increasing TCP window size

  • Tools: bbftp, sfcp, grid-ftp (new version of gsi-ftp)

Tim Adye

New ftp tools
New “ftp” tools

  • bbftp[Gilles Farrache, IN2P3]

    • Retry mechanism

    • On-the-fly compression

    • Now with ssh authentication option [TJA]

      • Greatly simplifies automatic operation

      • Allows access to bbrdist@datamove3

  • sfcp[Artem Trunov and Andy Hanushevsky, SLAC]

    • Better control of transfer parameters

    • Simple setup, but Solaris only

    • No compression, retry, etc.

Tim Adye

New ftp tools1
New “ftp” tools

  • grid-ftp (gsi-ftp) [GLOBUS]

    • GLOBUS authentication

    • Not yet publicly available

Tim Adye

Transfer performance
Transfer performance

  • SLAC->RAL Kanga exports

    • syncslac / rsync gave ~300 kbits/s per job

      • Scales with number of parallel copies

    • bbftp with 2 streams gives 3-6 Mbits/s

      • Nearing 10 Mbits/s Janet-ESnet peering

    • sfcp with 2 streams gives 600 kbits/s

      • Scales with number of streams

      • Need to understand sfcp/bbftp differences

  • RAL->SLAC SP imports

    • bbftp gives 10-20 Mbits/s

      • Benefits from x3 compression of Objy files

Tim Adye


  • The optimal bbftp/sfcp choice/settings will vary from site to site.

    • Rome->RAL: bbftp and sfcp are similar

    • Eg. SLAC<->INFN gain with larger number of streams

  • Need systematic tests to give better advice

Tim Adye

Kanga export procedures
Kanga export procedures

  • Kanga export controlled by skimData database

    • David Kirkby, Alessandra Forti, Alvise Dorego,TJA

  • skimSqlMirror makes local copy of skimData db

  • skimSqlSelectselects data for import

  • skimImportcopies the selected files

  • skimBackupbackup/archive to tape

  • skimDeleteremove files from local disk

  • Documentation under construction at


    • BaBar -> Computing -> Data Dist -> skimData remote

Tim Adye


  • Selects data for import by setting a flag in skimData database

  • Run as part of skimData mirroring to automatically select new data

  • Use skimData options to select data, eg.

    • skimSqlSelect

      -–skimData ‘-sAllEventsKanga:-S>=Skim880f’

Tim Adye


  • Copies files that are marked for import in the skimData database

  • Can use different ftp programs

    • Currently implements bbftp and sfcp

    • Plan to add rsync which can check existing files

    • Perl OO interface can be used by other scripts

      • Eg. Automatic SP export procedure

  • Can distribute files across different filesystems.

  • Eg.

    • skimImport --ftp-type=bbftp –config=ral.cfg

Tim Adye


Need guinea pigs to try this all out

Tim Adye