The Login Node¶
The login node is a shared resource with a hard limit of 1 CPU core and 1 GB of RAM per user. It is shared simultaneously by every user on the system. Running a compilation, a Python script that loads large datasets, or a Monte Carlo job — even briefly — degrades the experience for everyone and may result in your process being killed automatically by the system.
Think of the login node as the foyer of a library: a place to orient yourself, organize your materials, and submit requests. The reading rooms (compute nodes) are where the actual work gets done.
What the Login Node IS for¶
| ✅ Allowed | ❌ Not Allowed |
|---|---|
Editing source files (vim, nano, emacs) |
Compiling C++/Fortran code |
| Writing and submitting Slurm scripts | Running Python scripts with heavy computation |
Managing files (cp, mv, ls, tar) |
Loading large datasets or ROOT files |
Checking job status (squeue, sacct) |
Running Mathematica kernels |
Light scripting (small awk, grep, sed) |
Any make, cmake, pip install with builds |
| SSH port forwarding for Jupyter | Running parallel processes with mpirun |
What Happens if You Violate This?¶
The system enforces resource limits via cgroups. A process exceeding its CPU or memory allocation will be killed without warning. Repeated violations may result in a temporary suspension of your account. When in doubt, use an interactive session:
This command will create a slurm job with an interactive bash shell on one of the computing node.