General
Which filesystems do I have available? What is the intended usage?
Most of our machines use a shared filesystem (Lustre) across them, so all your data is accessible from your account in all of them. Also, quotas are enforced to limit user data on filesystem. Those machines present the following structure:
- /global/home
- /global/projects
- /global/scratch
Filesystems overview
| Filesystem | Intended | Permissions |
|---|---|---|
| /global/home | Personal files | User |
| /global/projects | Inputs and results or share data with your group | Group |
| /global/scratch | Temporary or intermediate files used | User |
What is the difference between the sbatch and srun commands?
The srun command has two different modes of operation. First, if not run within an existing job (i.e. not within a Slurm job allocation created by salloc or sbatch), then it will create a job allocation and spawn an application. If run within an existing allocation, the srun command only spawns the application. For this question, we will only address the first mode of operation and compare creating a job allocation using the sbatch and srun commands.
The srun command is designed for interactive use, with someone monitoring the output. The output of the application is seen as output of the srun command, typically at the user’s terminal. The sbatch command is designed to submit a script for later execution and its output is written to a file. Command options used in the job allocation are almost identical. The most noticeable difference in options is that the sbatch command supports the concept of job arrays, while srun does not. Another significant difference is in fault tolerance. Failures involving sbatch jobs typically result in the job being requeued and executed again, while failures involving srun typically result in an error message being generated with the expectation that the user will respond in an appropriate fashion.