The GridPP UserGuide

What's Next?

Uploading your software to CVMFS

To start with, and if your software package/packages is/are small enough, you can probably get away with uploading your software as LocalFiles with your Grid job (perhaps using an archive file).

In fact, you may prefer this approach as http-based CVMFS repositories are world-readable.

However, at some point you and/or your Virtual Organisation are going to want your own CVMFS repository. For small, UK-based VOs the best way to do this is on the RAL Tier-1 Stratum-0. Contact us to find out more about doing this - access to the repository is governed by your Grid certificate.

In short, the process of uploading your software amounts to:

  • Generating a proxy with DIRAC: as this will be used to determine who you are and which repository you are accessing;
  • Logging in to the repository: You can then log in to your CVMFS repository with:
$ gsissh -p 1975 cvmfs-upload01.gridpp.rl.ac.uk
Last login: [Date/time] from [hostname]

   _. _.   o| _ ._
  (_|(_||_|||(_)| |
       |

          Location: r89.harwell.europe hpd r89rack137
            Branch: cc34/cvmfs-uploader (sandbox)
         Archetype: ral-tier1
       Personality: cvmfs-uploader
  Operating System: sl640-x86_64
     Snapshot Date: 2016-10-26

[{vo-name}sgm@cvmfsXXXXX ~]$ cd cvmfs_repo
bin lib code README.md
  • Retrieve your software: You can now place your software in the repository, arranging it however works best for you. If your code is hosted in an online Git-based repository, simply git clone it straight to an appropriate directory.
You can take inspiration from other VOs. For example, you can browse the ATLAS experiment's (CERN-hosted) CVFMS repository with: $ ls /cvmfs/atlas.cern.ch/ and so on.
Once put into the repository, it can be several hours before it becomes available on the worker nodes - it's not instant. Make sure your software is well-tested before putting it up - CVMFS is not appropriate for software under development!

However, once it is on there, it's available everywhere. Which is nice.

Advanced DIRAC functionality

DIRAC has a great deal of functionality of its own, particularly when you start looking at the Python API. However, Ganga provides a nice wrapper for much of this so you shouldn't need to touch it. You can find out more on the DIRAC homepage, and check out the source code on their GitHub page.

Advanced Ganga functionality

Likewise, there is a lot more to Ganga than we have covered here. Ganga has its own documentation page: http://ganga.readthedocs.io which features things like:

  • Configuration;
  • Job manipulation;
  • Splitters;
  • Post-processors;
  • Queues;
  • Etc.

The GitHub repository is also worth watching for the latest updates and developments, as well as raising any bugs or problems you may have in the Issues section.

And finally...

Moving your workflow to the Grid won't necessarily be straightforward, but at GridPP we're here to help - if you've got a problem, just ask! To keep up to date with the UserGuide, watch the UserGuide GitHub repository to be notified of Issues and Pull Requests relating to additions or improvements to the UserGuide.

Many thanks for reading so far, and happy Gridding!

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