Optimizing SBATCH parameters

In order to create a sbatch for a script, you need to know how many resources the job will need to run. To get an estimate, you can run just a few subjects to get an idea of how much resources a single subject uses. We also have guidelines for how many resources each pipeline needs.

Run a few subjects with the pipeline. You can use the same 3-5 jobs you used for storage estimates to estimate job specifications.
Run seff on the jobs
- seff is used to check the memory utilization and CPU efficiency for completed jobs. Note that for running and failed jobs, the efficiency numbers reported by seff are not reliable so please use this tool only for successfully completed jobs.
- The job ID can be found first by using squeue -al –me , and it will be the number associated with the most recent job submission listed under “JOBID”
  - Use sacct -S YYYY-MM-DD -u x500 to find job IDs for past jobs that occurred after the specified start date.
- Command to run: seff job_id
- CPU Efficiency is calculated as the ratio of the actual core time from all cores divided by the number of cores requested divided by the run time.
- Memory Efficiency is calculated as the ratio of the maximum amount of RAM used by all tasks divided by the memory requested for the job.
- seff output example:
  - Nodes can be manipulated in the sbatch by the --nodes flag.
  - Cores per node can be manipulated with the --ntasks-per-node flag.
  - Job Wall-clock time is the length of the job in real hours, and can be manipulated with the -t or --time flags. Based on this output, a time specification of 72:00:00 should suffice.
  - Memory Utilized can be manipulated with the --mem flag. Based on this output, a 40 GB specification of memory will allow for a more efficient job versus 60 GB.
  - CPU Utilized is the total CPU hours that were allocated based on the request.
  - CPU Efficiency is the proportion of the CPU that was utilized for the job compared to the total core-walltime of the CPU.