The Globus Toolkit grid middleware makes the user's life easier by providing a uniform interface, hiding the idiosyncrasies of a wide variety of computing resources. Further, it provides a single sign-on mechanism: the user types the passphrase only once, even if many jobs are submitted to different resources. Besides DEISA, Globus is also being used world-wide by many flagship Grid projects such as TeraGrid.
In this chapter is presented instructions for job submission with Globus. There are separate DEISA User Guides for
There are basically two slightly different possibilities to use Globus: (i) from a DEISA computer, (ii) from your home computer.
(i) If you submit jobs from a DEISA computer, then the Globus environment is pre-configured and is ready to be used. Chose this mode of operation for first experiments or if you are new to Grid computing. In the following guide, we will focus on this mode of operation. However, this is not the normal Grid-like way to do things, especially if you also use resources outside of DEISA.
(ii) The more Grid-like way is to use Globus commands on your local machine and to submit jobs to DEISA and other Grids directly from there; however, you must set-up Globus on your local machine. Such instructions are beyond the scope of this guide. Please consult your local system administrator or look at the Globus web site or at its European counterpart.
We will now describe in a step-by-step how to submit computational jobs (including MPI parallel production jobs) through WS-GRAM to DEISA HPC resources.
For the single sign-on processes to work, Globus commands require certificate files. There are two types of certificate files: your private X.509 certificate and certificate files of those Certificate Authorities (CAs) which you trust. If you are using Globus commands at DEISA sites or the GSISSH-Term tool provided by DEISA then the CA certificates are set up for you automatically. If you submit Globus commands from your local machine then please refer to the certificates guide within the DEISA FAQ on how to set-up the CA certificates on your machine at http://www.deisa.eu/usersupport/user-documentation/faq/CertificatesFAQ.
The easiest way to start using Globus commands is to use DEISA's Java GSISSH-Term which permits users to login to DEISA HPC systems via the public Internet.
Currently, DEISA sites provide Globus 4.0 WS-GRAM service as an Optional Service, meaning that it may not be available at every site by default. If you need Globus WS-GRAM at a site where it is not available, please submit a request to DEISA.