Difference: LHCComputingGrid (13 vs. 14)

Revision 142006-04-10 - 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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 The files are stored on Storage Elements on the LCG. Usually these have different physical file administration schemes. Therefore, a logical layer was built on top of them, which makes the file access uniform from the user point of view. To use this facility , use the environmental variable LCG_CATALOG_TYPE:

export LCG_CATALOG_TYPE=lfc
(for bash), or
Changed:
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<
setenv LCG_CATALOG_TYPE lfc (for tcsh).
>
>
setenv LCG_CATALOG_TYPE lfc
(for tcsh).
  The Logical File Name (lfn) is resolved by the Logical File Catalogue (lfc) server. You have to specify this:

export LFC_HOST=lfc-cms.cern.ch
(for bash), or
Changed:
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<
setenv LFC_HOST lfc-cms.cern.ch (for tcsh).
>
>
setenv LFC_HOST lfc-cms.cern.ch
(for tcsh).
  Now you can refer to files with their logical file names, which are site-independent. The logical file names have to be unique. A very convenient way to generate them is to imitate the UNIX type file naming scheme. With the command lfc-mkdir one can make logical directories, like
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  You can get the library files here: pstream.h, gstream.h, gstream.cc. Before you can use it you have to export the following environmental variables:
Changed:
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export VO=your_vo
(for bash), or setenv VO your_vo (for tcsh), and
>
>
export VO=your_vo
(for bash), or
setenv VO your_vo
(for tcsh), and
 
export DEST=your_favourite_storage_element
(for bash), or
Changed:
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<
setenv DEST your_favourite_storage_element (for tcsh).
>
>
setenv DEST your_favourite_storage_element
(for tcsh).
  Setting the environmental variable TMPDIR is optional. This specifies the local (or AFS) directory, where the datafiles are staged out (therefore, it has to have large disk space!). E.g.:
Changed:
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export TMPDIR=/tmp
(for bash), or setenv TMPDIR /tmp (for tcsh).
>
>
export TMPDIR=/tmp
(for bash), or
setenv TMPDIR /tmp
(for tcsh).
  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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