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Job Parameters

Job Parameters

This page gives a short overview of the most important computing job parameters. For a full list consult the Slurm documentation.

If you need help writing job scripts or submitting jobs to the Slurm queue, please consult the provided tutorial.

Note: Job parameters can be specified in a short and long form. The short form requires a space after the parameter, whereas the long form requires an "=" without any whitespace. Examples are provided below for clarity.

Table of Content


Setting the Job Name

  • long format: --job-name
  • short format: -J
  • example: -J my_job
  • default: interactive when using salloc and the name of the job script when using sbatch
  • remarks: Avoid using special characters. Only alphanumeric are recommended.

Setting the Run Time

  • long format: --time
  • short format: -t
  • example: --time=1-05:10:15 (1 day, 5 hours, 10 minutes, 15 seconds)
  • default: 15 minutes
  • remarks: Mind the maximum job run time of your computing project.

Selecting the Output File

  • long format: --output
  • short format: -o
  • example: -o /home/ab123456/results.out
  • default: output_%j.txt where %j is the job reference number
  • remarks: Do not use ~ or variables like $HOME as path! Use full, explicit paths as shown in the example. Combine STDERR with STDOUT for easier error analysis by avoiding the --error parameter.

Setting the Number of Cores

Depending on your use case one or multiple of the following options can be set:

CPUs per Task (usually is used for OpenMP or Hybrid parallelisation)

  • long format: --cpus-per-task
  • short format: -c
  • example: -c 10
  • default: 1

Number of Tasks (usually used for MPI parallelisation)

  • long format: --ntasks
  • short format: -n
  • example: -c 10
  • default: 1

Number of Tasks per Node

  • long format: --ntasks-per-node
  • example: --ntasks-per-node 2

Number of Nodes

  • long format: --nodes
  • short format: -N
  • example: -N 1
  • default: will be set according to number of tasks

Setting the Memory

  • long format: --mem-per-cpu
  • example: --mem-per-cpu 5G (5GB per core)
  • default: Depends of the selected partition. For c23ms it is 2.6 GB.
  • remarks: Usually you do not need to set this parameter, as the default will get you the maximum memory without being billed for more cores. It is therefore also not neccessary to set the parameter --mem.

Submitting with a Project

  • long format: --account
  • short format: -A
  • example: -A rwthXXXX
  • default: your personal quota
  • remarks: You must be a member of the computing time project to charge computing time to it.

Submitting a GPU Job

  • long format: --gres=gpu:<N>
  • example: --gres=gpu:2 (requests two GPUs)
  • default: none
  • remarks: <N> is the number of GPUs that you want. Mind that your project needs to be allowed to use GPUs.

Submitting to a specific Partition

Depending on your computational needs you may want to specify a specific partition on the cluster.

  • long format: --partition
  • short format: -p
  • example: -p c23ms
  • default: depends on your project

Using BeeOND

  • long format: --beeond
  • default: BeeOND is not used
  • remarks: Details on how to use BeeOND (BeeGFS On-Demand) can be found on the page about the available filesystems. Please mind that your job will become exclusive if you use BeeOND.

See also

 

last changed on 05/16/2024

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