Overview

Software on our cluster can come from many places.

1. Software that comes with the Operating System
2. Custom software installed by your experiment
3. Other software installed by your local system administrator

Software that comes with the Operating System

Normally you would not need to do anything special to use this software except know the name of the command to run it. The operating system normally provides only one very stable but normally very old version of a particular piece of software. This is often all you need and is a good thing to try first.

Software that comes from your experimental group

Your experiment may provide their own way of installing software. Particle Physics Linux team have some involvement in this, but normally the best place to start is by asking members of your group. For multi-site collaborations, often your software will be installed somewhere under /cvmfs. The way to set up your environment to use this software will be specific to your experiment.

Usually experimental software sets up the environment for a whole host of different packages different from the operating system version.

Software maintained by Particle Physics Linux Team

We can also set up packages and versions of standard software that can not be found or are inappropriate for the categories above. We use "environment modules" to provide a way to cleanly maintain multiple versions of a particular piece of software on the system. We can also offer the most help with these when things go wrong. Environment modules providing a particular piece of software need to be loaded before the software works. General instructions can be found at the following page: linux-network-software

Compatibility

• You can usually expect packages within your experimental software to be compatible within one release from your experiment on the operating system it was intended for. Mixed environments from different versions of the software released by your experiment may break in unexpected ways. Avoid mixing environments or if you do, mix in one package at a time.
• You can expect that all managed packages (modules) are either compatible with each other or will flag an incompatibility when loaded on the operating system for which they were intended.
• Mixed environments between experimental software and managed software may be incompatible. Often this will be seen first if different versions of the compiler or python are used. Mix in one package at a time. Modules and experimental set-up scripts can and usually do load multiple packages at once to bring in all dependencies.