There are a few different ways to run a job on SESYNC’s Slurm compute cluster, but all of them ultimately run a command called
sbatch to submit the job to the cluster. The
sbatch program is part of the Slurm software package and has a lot of different options. These include a maximum length of time your jobs can run, how much memory you are requesting, whether you want to be notified by email when your job finishes running, etc. It’s possible to run a Slurm job without setting any of the options and going with all defaults, but there are times when you might want to customize the options.
The official help documentation for sbatch is great, but it’s a lot to wade through. Here are some common SESYNC-specific options that you might want to set on your Slurm jobs, and how to set them either from the command line or through the rslurm package.
If you are submitting a Slurm job from the command line directly, you include the options with your call to
sbatch. For example if you want to submit a job with four array tasks called
cool_job that runs a shell script called
my_script.sh you could write:
sbatch --job-name=cool_job --array=1-4 my_script.sh
Alternatively, some options have single-letter (case-sensitive!) shortcuts so this is equivalent to the above. Note: you do not use an equal sign when using these shortcuts.
sbatch -J cool_job -a 1-4 myscript.sh
If you are submitting a Slurm job using the rslurm package, some of the options are included in the default arguments to
output. If you want to specify any other options not included in the default arguments, pass them as a named list to the
slurm_options argument. You cannot use the single-letter shortcuts through rslurm!
For example, let’s say you want to specify that your job called
cool_job that runs an R function called
my_function() is only for testing purposes and should only run on one of the two low-capacity test nodes. You can specify that the job should run on the sesynctest partition by writing your call to
slurm_apply() like this:
slurm_apply(my_function, my_data, jobname = 'cool_job', nodes = 1, cpus_per_node = 4, slurm_options = list(partition = 'sesynctest'))
As promised above, here is a table with the SESYNC-specific options that we have found the most useful for running cluster jobs, in roughly descending order of how important they are. See the help documentation for sbatch for more details and more options.
Some options to especially consider if your jobs often run out of memory are
--nodelist. See more details in the table.
|Name||Shortcut||Example||What it does||Included in rslurm?|
||How many copies of the script to run. In the example, the
||Which group of nodes to submit the job to (more info here).||no|
||The job’s name, of course!||yes|
||List of nodes to run your job on. At SESYNC, you will really only need this to specify the high-memory nodes, which are nodes 44-47 on the
||If you set this option to
||Variables you want to pass to the job script. See details below2.||no|
||Maximum time your job will run before being killed. At SESYNC, you only need to specify this if a scheduled maintenance outage is coming up and you want your job to run before the outage begins.||no|
||How many parallel processes your job will start (most SESYNC nodes have eight processors)||yes|
||How many nodes to request (each node has multiple processors so you can run parallel code within a single node)||yes|
||How many processors are needed for a single task (if a single task needs a lot of memory, you may need more than one processor per task)||yes|
||How much memory to allocate to each CPU on a node. Most nodes have 60GB of memory, so this effectively limits the number of processes that can simultaneously run on a node.||no|
||A list of events that will cause the job to send you an email, usually when it finishes or is killed.||no|
Also, try filtering the FAQ and Quickstart pages by the “Slurm” tag for more information!
Note on –export: This is very useful if you have a general job script that you want to run at different times with different input files. For example if you write
sbatch will pass two strings to the job script, one for the name of the input file and out for the name of the output file. Your job script will need to refer to those two variable names. ↩