The GILDA t-Infrastructure

Educational Program

The term t-Infrastructure indicates an e-Infrastructure adapted to the needs of education, trainers and students. Shared t-Infrastructure would be usable by students and teachers internationally, providing easy access to educational exercises running on e-Infrastructure.

GILDA (https://gilda.ct.infn.it) officially started at the beginning of 2004 as an initiative of INFN in the context of the INFN Grid Project (grid.infn.it) and the European EGEE project. The purpose of GILDA was to create a test-bed entirely dedicated to training and dissemination, based on gLite middleware (www.glite.org) services, comprising of the most useful facilities such as a dedicated Certification Authority and a Virtual Organization and monitoring and support systems for users.
Besides the support for training events, GILDA has also been used around the clock in the years by beginners, users or sites, wishing to start their Grid experience.

During these four years, more than 200 training and dissemination events have been supported by GILDA. The level of support went from the simple release of certificates (more than 10000 certificates have been issued since the beginning) to the creation of accounts and demonstrative applications on the resources for the full use of the training infrastructure during the events.
While supporting this large number of events, lots of problems have been faced and their solutions have become a series of best-practices in Grid education now usually adopted worldwide.
- Loose identification procedures for hosts and personal user certificates: the strict identification required from a “real” Certification Authority can be discouraging for new users and it can be considered not really necessary when approaching the Grid for the first time. Users have just to fill in a web form, and the certificate will be signed and sent to the email address of the requestor. This practice has clearly increased the number of certificates released, reducing the errors to which a non-experienced user is exposed and making this first, and usually error prone, step a lot easier. The risks that could derive from this non-strict identification, such as a misuse of the certificate, are mitigated by the small scope and time duration of these certificates: typically, just the GILDA test-bed itself, and two weeks, by default.

- Use of generic certificates and accounts for tutorials: in the first supported tutorials, users were contacted one or two days before the tutorial, and they were requested to ask for a personal GILDA certificate. As a matter of fact, most of them ignored these email. Many who did complete the certificate request correctly subsequently forgot to bring their certificates with them as advised, leaving them on their own machines. Requesting the certificate during the tutorial was not an effective solution, because the requests, and the various problems which may arise, made it impossible to support all participants quickly. This problem has been solved by forcing the tutorial organizer to specify the expected number of participants. Then, the GILDA CA manager issues the number of generic certificates requested and these are also exported in the requested format. System accounts are created on the official GILDA User Interface machines, and the certificates are copied in there. If the tutorial organizers plan to use different UI's, they can even request for the certificates to be sent separately. This practice also has the risk that certificates can be misused but this is mitigated by the fact that certificates are valid just for the duration of the tutorial, and they also have a limited scope.

- Use of wiki pages for on-off/line training: the most used training instruments in the beginning of GILDA have been transparencies. This practice proved to be not very effective, especially for exercises, for at least a couple of reasons. First, they offer a limited space for editing text, which is really a problem when reporting long option commands or command outputs. Second, it is hard to continuously maintain and update them in case of errors or changes due to new middleware releases. To face this issue, a wiki site has been setup in EPIKH Proposal no. 230842 2 September 2008 70/83 GILDA. The choice of the wiki site was also motivated by the fact that it enhances the collaboration among trainers without requiring physical access to the web server.

- Use of virtual machines for training: virtual machines have been proven to be a very effective instrument for Grid site administration tutorials, i.e. those training events where attendees learn how to install and operate Grid services. Since this exercise needs always a machine installed from scratch, the use of real machines is a clear limitation, because requires both a large number of available boxes and a huge amount of time to reinstall the machine from scratch for each Grid element. Virtual machines allow learners to start always from a preloaded image containing just the flat operating system. Students install the Grid service and then, once the exercise is finished, they have just to shutdown the virtual machine, reload the flat image, and they can start the next exercise in just a few minutes.

Also, virtual machines are effectively used for dissemination purposes since they have been made available from the GILDA web site with several preinstalled Grid elements ready to be downloaded by users who wish to play with Grid elements even if they can't install a real machine or they don't have the opportunity to set up a full featured Grid.

Last Updated on Wednesday, 04 March 2009 13:38