Important differences between Slurm and Torque

• Environment at job start:

  • Torque does by default start with the login environment of a user.

  • Slurm starts by default with the environment from which the job was submitted (essentially the effect of qsub -V in Torque). This can have unexpected results, e.g., if you resubmit the job from a different environment or if some things are in different directories on the login and cluster nodes which does sometimes happen when we do a silent upgrade of the cluster.

    • --get-user-env will give an environment pretty equivalent to what you would get on Torque

    • --export=NONE will start the job with a very empty environment

• Working directory at job start: This is in fact a logical consequence of the previous bullet.

  • In Torque, the job start in your home directory. You can go to the directory from which the job was submitted with cd $PBS_O_WORKDIR.

  • In Slurm, a job starts in the directory from which the job was submitted.

• Redirection of stdout and stderr:

  • In Torque, stdout and stderr go to different files by default. Both streams can be merged in a single file as in Slurm by specifying -j oe in the job script or at the qsub command line.

  • In Slurm, stdout and stderr are merged into a single file by default. You can change the behaviour by specifying a filename for stderr using --output-err.