HPC/Module naming scheme 2016

Configuration files used

You have files: .bashrc and …		Remark	CentOS-5 uses		CentOS-6 uses
			module names	files	module names	files
–	–	current situation	old	.bashrc only	new	.bashrc only
–	.modules-carbon-2	switch over, recommended	new	.modules-carbon-2 and .bashrc		.modules-carbon-2 and .bashrc
.modules-carbon-1	–	avoid	old	.modules-carbon-1 and .bashrc		.bashrc only (.*-1 file is ignored)
.modules-carbon-1	.modules-carbon-2	for advanced users	old	.modules-carbon-1 and .bashrc		.modules-carbon-2 and .bashrc

Configuration steps

CentOS-independent module selection (recommended)

To switch over to new hierarchical module names on both CentOS releases it's easiest to continue making all your module choices in ~/.bashrc, but you have to signal on the older platform to use the new module style:

1. Create a customization file for new names, but leave it empty (you'll configure your choices in the next step). Use the command:

   touch ~/.modules-carbon-2
   

2. Edit your .bashrc file and update your module selections as follows:
   • Remove version numbers from module names of the old-style packagename/version, leaving only packagename. This is the recommended approach, as you will automatically benefit from future versions.
   • To insist on a specific version for a pacakge affected by the new-style names, use the form packagename/compilername/version or packagename/mpiname/compilername/version as appropriate. To see available flavors and versions, separately run the command module avail packagename.

CentOS-dependent module selection

If you encounter difficulties with making your module selection work in both CentOS-5 and CentOS-6, use separate configurations:

1. Move all your previous module commands from .bashrc to ~/.modules-carbon-1, where they will apply only on CentOS-5.
2. Place all your module selections for CentOS-6 in ~/.modules-carbon-2. To begin, it will of course be simplest to copy the .*-1 file as *.2 and edit the latter.

New and changed features

Module dependencies

New-style modules are less implicit (less automatic and less rigid) in loading modules that they depend on.

• Less automatic means that prior to loading a more advanced module you must load all its prerequisites, chosen from the same MPI and (usually) compiler flavor as the advanced module. A missing prerequisite will give errors of the form

… ERROR:151: Module 'troubled_name' depends on one of the module(s) 'other_name1 other_name2' …

To resolve this error, edit your ~/.bashrc or .modules-carbon-2 file and add module load … commands for the needed module(s) other_names before loading "troubled_name".

• Less rigid means that a module does not loads a specific version of a prerequisite, which gives you, the user, more flexibility in combining modules.

Name completion

When working interactively in a terminal, you can use a "completion" feature of the Bash shell to complete a partially typed module name and show all names available for the name typed so far. For example:

At a shell prompt (shown as "$"), type:

$ module load fft

Press the <TAB> key and the name will be expanded to fftw3/ and you'll see two possible completing names, with the cursor waiting at the end of the longest common substring:

$ module load fftw3/_
fftw3/INTEL/3.3.2-1              fftw3/OPENMPI-1.4/INTEL/3.3.2-4  

Type the letter O, hit the <TAB> key again, and the now single complete name will be completed, with the cursor waiting after an additional space character:

$ module load fftw3/O<TAB>
$ module module load fftw3/OPENMPI-1.4/INTEL/3.3.2-4 _

Ignoring system defaults

By default, on Carbon the Intel compilers and the OpenMPI flavor of MPI continue to be pre-loaded for you. In other words, without any module customization, you'd see from the module list command:

module list

Currently Loaded Modulefiles:
  1) intel/15/15.0.2                     2) openmpi/1.4/INTEL/1.4.5-intel12-2

You can now safely use the command

module purge

and afterwards use module load … to only load your preferred compiler and MPI flavors, and applications depending on them.