US ATLAS SW Infrastructure
Information for new users of U.S. ATLAS TIER I center
 

This page is not updated since December 2005. Please refer to U.S. ATLAS Software Support Wiki for up-to-date information.


* Accounts, file systems, computers

Please refer to the Tier I Computing Facility (ACF) help pages for details on accounts, file systems, and ACF computers. Here is a short summary.


* Login environment

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The environment variables for ATLAS software releases are installed by the CMT release tool (CMT setup procedures are described here ). For instance, the proper versions of compilers and external packages, such as ROOT, are inserted in $PATH and $LD_LIBRARY_PATH. The U.S. ATLAS accounts get automatically the standard login files in their home directories, such as .bashrc and .cshrc, with the following contents:
if ( -r /usr/local/lib/hepix/shells/hep/central_env.[c]sh ) then
   source /usr/local/lib/hepix/shells/hep/central_env.[c]sh
endif
This installs initial (very basic) U.S. ATLAS environment by sourcing a file on the central file server. A user can add its own definitions in login files if desired.


* Organization of ATLAS software

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ATLAS software is organized in large software releases (730 packages as of January 2004). New stable development releases of atlas software are produced in three weeks intervals (there are also nightly builds for checking the latest submissions, but beginners are not encouraged to use them). The names of stable ATLAS releases are X.Y.Z, where X,Y,Z = 0 - 9. The "production" ATLAS releases have Y = 0, all other releases are "development". ATLAS software releases depend on many external packages (about 57 as of January 2004). The main OO framework, ATHENA, is based on the GAUDI architecture that is technically also an external package.

At the U.S. ATLAS Tier I Computing Facility the software organization mirrors the CERN ATLAS site. The major areas are

Further details are available at our page ATLAS software releases and how to use them .

ATLAS software release consists of install area (InstallArea) and directories of packages. Install area contains references (soft links) to binaries, includes and share files dispersed in the release tree. ATLAS releases are managed by CMT release tool. The packages are organized according to CMT principles and can be simple packages (with no subpackages) or containers of simple packages and/or subcontainers. A CMT package consists of the version directory(ies) containing areas with sources, binaries, and cmt directory with CMT configuration (usually stored in single requirements file). Theoretically CMT allows multiple versions of one package in the release, however in ATLAS releases all packages have single version.


* Work model

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CMT managerial principles and mechanisms are used in all stages of work (setting environment, compilation, linking, running) and they are evolving with ATLAS software. This means that the particular ATLAS releases must be handled with specific version of CMT. In addition the procedures for setting working environment vary for different releases. The helper scripts for automatic environment tuning have been developed for U.S. ATLAS users. The basic model of ATLAS software development include the following steps (click on links for concrete recipes):

  1. Setting general environment that includes:
  2. Creating work release with one or more ATLAS packages. This could be the code that a user is going to develop or packages that help to connect to the software release and acquire settings from the packages of this release. U.S. ATLAS users can conveniently check out ATLAS packages to their work areas from local mirror of ATLAS CVS repository. Checkouts should be performed with cmt co command because it creates the correct directory hierarchy.
  3. Setting work environment is performed by sourcing setup.(c)sh script (generated by cmt co) in cmt directory of a package. As well in this directory CMT generates Makefile, so the compilation and linking is performed with standard (g)make. Sourcing setup.(c)sh provides also a run time environment for jobs associated with the package.
  4. Running ATHENA jobs. In ATLAS software network there is a single application athena that loads components dynamically at run-time. The components (ATHENA algorithms and services) and job parameters are specified in jobOptions files located in the share directories of packages (and also referenced in InstallArea). Therefore all kinds of jobs (simulation, calibration, reconstruction...) are performed with standard command
    athena <package name/specific jobOption>
    and run time environment provided by CMT mechanisms.


*Relevant links

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