🚀 Using CPLEX on IDUN (NTNU HPC)

IBM ILOG CPLEX is a powerful optimization solver widely used in energy systems, operations research, and large-scale optimization problems.

On NTNU’s HPC cluster IDUN, there are two main ways to install and use CPLEX:

  • ✅ EasyBuild installation (recommended)
  • ⚙️ Manual installation

This guide is based on practical experience and internal instructions from NTNU HPC support.

📦 Before You Start

Before installing CPLEX:

  1. Accept the IBM academic license
  2. Download the Linux installer:

👉 https://academic.ibm.com/a2mt/downloads/data_science#/

Download:

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cplex_studio2211.linux_x86_64.bin

🌐 Download Interface

CPLEX download page

  • Find IBM ILOG CPLEX Optimization Studio
  • Select Linux version
  • Download the .bin installer

CPLEX Linux download

Upload the file to your home directory on IDUN.

⚡ Method 1: EasyBuild Installation (Recommended)

This is the cleanest and most stable method on IDUN.

1. Load EasyBuild

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module purge
module load EasyBuild/4.9.0

2. Check available versions

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eb -S cplex

Example output:

  • CPLEX-12.9
  • CPLEX-12.10
  • CPLEX-22.1.1

3. Prepare source directory

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mkdir -p $HOME/.local/easybuild/sources
cp -ip cplex_studio2211.linux_x86_64.bin $HOME/.local/easybuild/sources

4. Dry run (optional)

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eb -D CPLEX-22.1.1.eb --robot

5. Install CPLEX

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eb CPLEX-22.1.1.eb --robot

⏱️ Installation takes ~2–3 minutes

6. Clean environment

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module purge

▶️ Using CPLEX

Add module path (important)

Add this to your .bashrc:

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export MODULEPATH=$MODULEPATH:$HOME/.local/easybuild/modules/all

Load CPLEX

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module spider cplex
module load CPLEX/22.1.1

Start CPLEX

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cplex

Exit:

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quit

Optional: Use with Julia

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module load Julia/1.9.3-linux-x86_64
julia

⚙️ Method 2: Manual Installation

Use this only if you need custom setup.

1. Make installer executable

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chmod +x cplex_studioXXX.linux-x86-64.bin

or:

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sh cplex_studioXXX.linux-x86-64.bin

2. Run installer

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./cplex_studioXXX.linux-x86-64.bin

3. Installation directory

Use absolute path:

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/cluster/home/<your_username>/opt/ibm/ILOG/CPLEX_Studio2211

4. Install Python API

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cd opt/ibm/ILOG/CPLEX_Studio2211/python
python setup.py install

Optional (Conda):

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export PYTHONPATH="/home/<your_username>/.conda/envs/my_env/lib/python3.8/site-packages:$PYTHONPATH"

5. Pyomo Solver Fix

If standard solver fails:

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opt = SolverFactory('cplex_direct')

💡 Notes & Tips

  • EasyBuild integrates cleanly with IDUN modules
  • Avoid using relative paths for installation
  • Always use absolute paths on HPC systems
  • Prefer module-based workflows

📚 Available Versions

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eb -S cplex

Available:

  • CPLEX-12.9
  • CPLEX-12.10
  • CPLEX-22.1.1

📚 Additional Resources

🧠 Final Thoughts

For most research workflows (Pyomo, Julia, stochastic optimization), EasyBuild is strongly recommended.

Manual installation should only be used when customization is required.

👨‍💻 Acknowledgement

This guide is adapted from internal NTNU HPC instructions and shared notes from colleagues.
Special Thanks to Nora, Sina and Anders Gytri’s help on the IDUN documentation support.

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