Working with the Grid

temporary unofficial collection of useful information

URLs

GRID Certification -- instructions by the French authorities, very clear and general. Includes check of the certificate.
VOMRS - VO registration for ATLAS (user interface)
GSI: User's Guide -- under construction
ATLAS user support
Certification Authorities -- CNRS web page
Start Using the Grid: Overview -- BNL site
Describes how to download the certificate into the browser; how to export the certificate from the browser into the directory .globus and transform it for use with the Grid. Well understandable step by step description.
User guide for GRID resources -- obsolete, replaced by above site
US-ATLAS Instructions -- mirror of BNL USATLAS TWiki
Getting a Grid certificate -- instructions for BPhys group (by James Catmore)

Tutorials

Tutorial Grille -- LAL - Orsay (France), Oct 2007 (in french)

Scratch space on GRID

Part of the site configuration in LCG is the environment variable EDG_WL_SCRATCH. Users are supposed to create temporary files in the directory referred to by EDG_WL_SCRATCH. Do not use the /tmp directory on worker nodes.

Additional useful pages

Starting on the Grid -- StefanoAntonelliSandbox
Running the Full Chain on the Grid -- (Workbook) run job, save events to SE, read the events, locate the files
Using the Grid -- UCL HEP pages
A user's page -- check what is general (CatrinBernius)

Useful commands

>   grid-proxy-init    {Activate your Grid certificate}
	>   lcg-infosites --vo atlas se    {get list of storage elements SEs}
	>   lfc-mkdir -p /grid/atlas/users/$USER    {$USER is your login name or preferred identifier}

Change pass phrase

Note that there is the password, when you backup (or export) from the browser to the $HOME/.globus directory, and the passphrase when converting from the browser file *.p12 to the file userkey.pem.

>   grid-change-pass-phrase -file $HOME/.globus/userkey.pem
				or
				>   openssl rsa -in $HOME/.globus/userkey.pem -des3   {give old passphrase and then new one)

qstat

Query the status of queues at the CE, examples

 >   qstat -Q atlas    {status of queue "atlas"}
               >   qstat -r    {jobs currently running}

User support and reporting problems

Global Grid user support -- GGUS
atlas-user-support -- problems with replicating data from the grid to your local machines

Mixed bag

AFS cannot be addressed from Grid, e.g. for writing output files.