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SLURM

SLURM (Simple Linux Utility for Resource Management) is the workload manager used on the KSU HPC cluster. It is an open-source, highly scalable job scheduler designed for large and small Linux clusters. SLURM manages job submission, resource allocation, and job monitoring.

Warning

All jobs on this cluster must specify a valid billing account using the -A or --account option. - Example: sbatch -A research job.sh - Example: interact -A teaching -N 1 -n 4 -t 2:00:00

To avoid typing -A <billing_acct> each time, set the appropriate environment variables in your shell startup file (e.g. .bashrc):

export SBATCH_ACCOUNT=research
export SRUN_ACCOUNT=research
export SALLOC_ACCOUNT=research

Inside a running job, SLURM also defines SLURM_JOB_ACCOUNT to indicate the billing account in use.

Submitting Jobs

Jobs are submitted to SLURM using the sbatch command along with a job script. A basic job script looks like this:

#!/bin/bash
#SBATCH --job-name=test
#SBATCH --output=job.out
#SBATCH --error=job.err
#SBATCH --time=01:00:00
#SBATCH --nodes=1
#SBATCH --ntasks=1
#SBATCH --mem=2G
#SBATCH --account=research

hostname

Submit the job with:

sbatch -A research job.sh

Interactive Jobs

The recommended way to start an interactive session on the cluster is to use the interact wrapper script. This utility calls salloc under the hood, but provides a simpler interface and adds cluster-specific options.

Using interact

Basic example (defaults to 1 node, 2 tasks, 1 hour):

interact -A research

Request 1 node with 4 tasks for 2 hours:

interact -A research -N 1 -n 4 -t 2:00:00

Enable X11 forwarding for graphical applications:

interact -A research -X

Request a GPU with exclusive compute mode:

interact -A research -G -C exclusive

Run with a different shell:

interact -A research -s /bin/zsh

See all options:

interact -h

Note

The interact script respects the same environment variables as the native SLURM commands: SBATCH_ACCOUNT, SRUN_ACCOUNT, and SALLOC_ACCOUNT. Setting these in your .bashrc or .bash_profile ensures consistent defaults across sbatch, salloc, srun, and interact.

Advanced: Using salloc Directly

For users who prefer raw SLURM commands, you can request an allocation with salloc:

salloc -A research --nodes=1 --ntasks=2 --time=01:00:00 --mem=2G

Once your session starts, you’ll be placed on a compute node. Launch commands inside the allocation with srun, for example:

srun hostname

Note

interact is the preferred interface for most users. salloc is available for advanced usage and scripting.

Job Options

SLURM job options are set with #SBATCH directives in the job script or as command-line arguments to sbatch.

Common options include:

  • --job-name=<name>: Sets the job name.
  • --output=<file>: Path for standard output.
  • --error=<file>: Path for standard error.
  • --time=HH:MM:SS: Walltime limit.
  • --nodes=<N>: Number of nodes.
  • --ntasks=<N>: Total number of tasks (MPI processes).
  • --cpus-per-task=<N>: Number of CPUs for each task (for threaded codes).
  • --mem=<size>: Memory required (per node).
  • --account=<billing_acct>: Billing account to charge the job against. Required.
  • --partition=<queue>: Partition (queue) to submit the job to.

Monitoring Jobs

To view only your jobs:

squeue -u $USER

To view all jobs you are allowed to see:

squeue

To filter jobs by billing account (useful if you have access to more than one):

squeue -A research

To view details about a specific job:

scontrol show job <jobid>

View all your jobs (completed and running)

sacct -u $USER

(Optional) Filter by billing account if you have more than one

sacct -A research -u $USER

Canceling Jobs

To cancel a job:

scancel <jobid>

To cancel all your jobs under a billing account:

scancel -A research -u $USER

Example: Parallel Jobs with MPI

#!/bin/bash
#SBATCH --job-name=mpi_test
#SBATCH --nodes=2
#SBATCH --ntasks-per-node=16
#SBATCH --time=02:00:00
#SBATCH --mem=4G
#SBATCH --account=research

module load openmpi
srun ./my_mpi_program

Example: Shared Memory Jobs (OpenMP)

#!/bin/bash
#SBATCH --job-name=omp_test
#SBATCH --nodes=1
#SBATCH --ntasks=1
#SBATCH --cpus-per-task=8
#SBATCH --time=01:00:00
#SBATCH --mem=8G
#SBATCH --account=research

export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK
./my_openmp_program

Useful Commands

  • sbatch -A <billing_acct> script.sh — Submit a batch job.
  • interact -A <billing_acct> — Start an interactive session.
  • salloc -A <billing_acct> — Advanced interactive allocation.
  • srun — Run a job interactively inside an allocation or launch tasks in a batch job.
  • squeue -u $USER — View your pending and running jobs. (-A <billing_acct> optional to filter.)
  • sacct -u $USER — View your completed and running jobs. (-A <billing_acct> optional to filter.)
  • scontrol show job <jobid> — Show detailed information about a job.
  • scancel <jobid> — Cancel a job. (-A <billing_acct> optional to filter multiple jobs.)

More Information