Grid Data Management Client Tools

There are a number of data management tools available in LCG-2 that a user can exploit. The main tools are packaged as lcg_utils. These lcg utility commands comprise generic file and replica management tools and are the most useful utilities for users.

Preamble

UI Account and Valid Proxy Certificate

The following instructions assume that you have a User Interface (UI) account and have attained a valid proxy certificate (i.e executed the $ grid-proxy-init command). See LCG User Guide and Getting Started for more details.

File Catalogs and Storage Elements

At the time of writing (May 2006) the File Catalogs used in LCG have moved completely from the old European Data Grid (LRC/RLS) ones to the more modern LCG File Catalog.

It is possible to get a list of Storage Elements (SE) that can be utilised to host files by typing the following command
$ lcg-infosites --vo MY_VO se
where "MY_VO" is, e.g., atlas, alice, cms or lhcb. When it has completed execution you see the hostnames of all the storage elements on the grid which support your VO. These locations are necessary for issuing certain commands, e.g., copying a file to a new one storage element

Transferring Files on and off the Grid

To copy files within grid resources e.g. SE -> SE or between grid resources and the outside world e.g SE -> UI -> local machine area the following tools are usually used, though your local site might support different methods of copying files to/from the UI
to copy a file from a local machine to a UI scp "secure copy" unix tool
to copy a file from a UI to a local machine scp "secure copy" unix tool
to copy a file from a UI to a SE lcg-cr "lcg-copy-and-register" grid datamanagement tool
to copy a file from a SE to a UI lcg-cp "lcg-copy" grid datamanagement tool
to copy a file from a SE to a SE lcg-rep "lcg-replicate" grid datamanagement tool

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