Grid School for MICE

The session will not be highly structured - we will work through the first parts of MICE Notes 246 and 247, covering Grid job submission and file storage, with the aim of running either G4Beamline or G4MICE jobs on the Grid using at least the native EGEE tools.

Requirements

To take part you will need:

You may also wish to bring along a copy of the gLite User Guide as it's a long document to read easily through a browser (print 2- or 4-up).

Getting a Certificate

The basic process is as follows:

  1. Use your web browser to apply to a suitable Certificate Authority (CA)
  2. Show ID in person to a CA representative (an "RA")
  3. When the certificate is granted, re-visit the CA site with the very same browser you used for the application to collect it.
  4. With the certificate in the browser, apply to join the VO (see below)
  5. Make a "backup" or "export" of the certificate; this will be a .p12 file on disk. The browser will ask you for a passphrase to secure it. This will be your "Grid passphrase" - make sure you remember it! Note that it can contain spaces, so you can use a longer phrase or sentence that's easier to remember and type.
  6. If the browser is on the laptop that you'll bring with you, then move the .p12 file to a safe place.
    Else put the .p12 file on your laptop, or somewhere you can SSH it from RAL.

Note that if you lose a copy of the certificate you will have to revoke it and get a new one issued, so I suggest avoiding putting it on USB sticks. You should also never keep it in a browser that other people might have access to, so if you applied from say a shared PC at home then you should keep a separate copy of the .p12 securely filed away on a floppy disk and delete it from the browser.

Your CA's website should have detailed guides on how to apply, backup and look after your certificate. Read and follow them carefully, especially any bits about "root certificates".

Unfortunately I can't tell you which CA you should use. It has to be one trusted by the EGEE/LCG Grid: if you're at CERN then use the CERN CA, else there will be a national CA; locate it via the EUGridPMA Map.

Joining the MICE VO

The procedure is being reviewed; currently you should:

  1. Go to the MICE VOMS server with your certificate in your browser. At the bottom of the page it should say
    You are logged in as "your DN" certified by "CA DN"
    where your DN is a string of gibberish involving your name - note it down as you will need it later.
  2. Fill out the application form behind the "New user registration" link
  3. E-mail your DN to Malcolm Ellis.
  4. There won't be any notification - after a couple of days check that your DN appears correctly on the list of users accessed via the "Administer the VO" link.

Note that you cannot access any VOMS server from the RAL Visitors' Network...

Materials

We'll basically look at

  1. Certificates and initialisation - what does VOMS do for us?
  2. Resources, matching and submission
  3. Monitoring, retrieval and working out what went wrong
  4. File handling and LFC
  5. MICE_GRID_PWD, MICE_HOME_SEID, "Environment" JDL attribute, Grid job environment

To submit a simple test job:
make sure your certificate is saved as .globus/usercred.p12 from your home directory with 400 permissions, then

voms-proxy-init -voms mice
( myproxy-init -d -n )
( glite-wms-job-list-match -a testMICE.jdl )
glite-wms-job-submit -a testMICE.jdl
glite-wms-job-status 'JobID'
glite-wms-job-output 'JobID'
cat /tmp/jobOutput/subID/hello.out
( myproxy-destroy -d )
voms-proxy-destroy
CSH wrapper and JDL for g4beamline - uses LFC for output storage
Ancient CSH wrapper and JDL for g4mice - does NOT work with above

See my MICE Grid hints at http://people.brunel.ac.uk/~eesrjjn/mice/mice_grid.htm.

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