Difference: LHCComputingGrid (10 vs. 11)

Revision 112006-03-19 - AndrasLaszlo

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 Getting access to LHC Computing Grid. One can find a brief introductory material at the RMKI's getting started page, where you can find information on how to get access to LCG. There are also simple examples on that page.

Some more practical information on running a typical job.

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  • Read/write C++ streams to storage elements of the LCG:
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As one does generally not want to always stage out the data files to a local disk by hand, and then process it, it is recommended to have read/write streams. Unfortunately, such official streams are not available, yet. Therefore I wrote grid storage i/o stream C++ classes (gstream, igstream, ogstream, like the usual C++ STL fstream, ifstream, ofstream file input/output stream classes; the letter 'g' standing for 'grid'). It does nothing else, but treats the file as a normal file, unless its name begins with the string /grid/. In this case, it stages out the datafile in question onto a local (or AFS) area, and then treats the local file as a normal file. One commonly faces the problem that the file not only has to be processed, but it also has to be passed through a filter programme. Therefore I also wrote pipe streams for grid storage (gpstream, igpstream, ogpstream), which are based on the ipstream and opstream classes of the library at http://pstreams.sourceforge.net (note the LGPL license!). Some practical examples:
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As one does generally not want to always stage out the data files to a local disk by hand, and then process it, it is recommended to have read/write streams. Unfortunately, such official streams are not available, yet. Therefore I wrote grid storage i/o stream C++ classes (gstream, igstream, ogstream, like the usual C++ STL fstream, ifstream, ofstream file input/output stream classes; the letter 'g' standing for 'grid'). It does nothing else, but treats the file as a normal file, unless its name begins with the string /grid/. In this case, it stages out the datafile in question onto a local (or AFS) area, and then treats the local file as a normal file. One commonly faces the problem that the file not only has to be processed, but it also has to be passed through a filter programme. Therefore I also wrote pipe streams for grid storage (igpstream, ogpstream), which are based on the ipstream and opstream classes of the library at http://pstreams.sourceforge.net (note the LGPL license!). Some practical examples:
 
#include "gstream.h"
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  ofile.close();

// Open the datafile for reading, through a filter program.

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igpstream ipfile("/grid/cms/alaszlo/some_datafile.gz", "gunzip --stdout %f");
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igpstream ipfile("/grid/cms/alaszlo/some_datafile.dat.gz", "gunzip --stdout %f");
  // Extract data from your datafile with 'igpstream::operator>>' or with 'igpstream::read(char*, int)'. // Close the datafile. ipfile.close();
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 If not specified, the current working directory ($PWD) is used, as this is recommended for grid jobs (the working nodes have large disk spaces).
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-- AndrasLaszlo - 17 Mar 2006
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-- AndrasLaszlo - 19 Mar 2006
 

META FILEATTACHMENT attr="" autoattached="1" comment="Framework for a simple job" date="1142615719" name="skeleton.tar.gz" path="skeleton.tar.gz" size="18566" user="Main.AndrasLaszlo" version="2"
 
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