Session 2 - Using Ganga to Access the Grid

In this session we will submit simple jobs to the grid and learn a little about the underlying grid tools.

Preparing your Grid Certificate

To run on the grid, you must have a valid grid certificate. Hopefully, you will all have this already! However, it may currently be still loaded in your browser and so you need to go through a few steps to export it to your userarea:

1) Set up the grid environment:

2) Create a .globus directory:

mkdir ~/.globus

3) First, export the grid certificate. This is browser dependent, but in Firefox do:

Edit -> Preferences -> Advanced -> View Certificates

Select you certificate and click on 'Backup'. You should then be requested to download your certificate. Download it to your .globus directory you created above as 'grid.p12'.

4) Now the certificate must be converted to the correct form by doing the following:

openssl pkcs12 -in mycert.pfx -clcerts -nokeys -out usercert.pem
openssl pkcs12 -in mycert.pfx -nocerts -out userkey.pem
chmod 400 userkey.pem
chmod 600 usercert.pem

5) Hopefully, everything should now be ready so to check it's all OK, do the following:

 voms-proxy-init

which should give something like this:

Your identity: /C=UK/O=eScience/OU=QueenMaryLondon/L=Physics/CN=steve lloyd
Enter GRID pass phrase for this identity:
Creating proxy .............................................................. Done
Your proxy is valid until: Tue Apr 12 22:03:18 2005

Starting Ganga with Grid Tools Enabled

Ganga has been configured to use the local installation of the Grid UI so you don't have to do any setup beforehand. Simply run Ganga without the --disableLCG option:

/home/slater/runGanga

You will then most likely be asked for the passphrase for your grid certificate after which you should be presented with the IPython prompt as before. However, now the LCG backend and corresponding grid tools have been enabled. To have a look at the options for the backend, use the help system:

help(LCG)

-- MarkSlater - 08 Dec 2008