See the "available memory" column in the "Node characteristics" table for each GP cluster for the Slurm specification of the maximum memory you can request on each node: Béluga, Cedar, Graham, Narval. If you request more memory than a node-type provides, your job will be constrained to run on higher-memory nodes, which may be fewer in number.Īdding to this confusion, Slurm interprets K, M, G, etc., as binary prefixes, so -mem=125G is equivalent to -mem=128000M. The effect of this is that each node-type has a maximum amount available to jobs - for instance, nominally "128G" nodes are typically configured to permit 125G of memory to user jobs. At Niagara only whole nodes are allocated along with all available memory, so a memory specification is not required there.Ī common source of confusion comes from the fact that some memory on a node is not available to the job (reserved for the OS, etc). On general-purpose ( GP) clusters a default memory amount of 256 MB per core will be allocated unless you make some other request. Memory may be requested with -mem-per-cpu (memory per core) or -mem (memory per node). Consider using an array job instead, or use sleep to space out calls to sbatch by one second or more. Submitting thousands of jobs at a time can cause Slurm to become unresponsive to other users. Please be cautious if you use a script to submit multiple Slurm jobs in a short time. Please note that the time limit will strongly affect how quickly the job is started, since longer jobs are eligible to run on fewer nodes. The acceptable time formats include "minutes", "minutes:seconds", "hours:minutes:seconds", "days-hours", "days-hours:minutes" and "days-hours:minutes:seconds". Will submit the above job script with a time limit of 30 minutes. You can also specify directives as command-line arguments to sbatch. You may also need to supply an account name ( -account). Compute Canada policies require that you supply at least a time limit ( -time) for each job. All available directives are described on the sbatch page. On Niagara this job reserves the whole node with all its memory.ĭirectives (or "options") in the job script are prefixed with #SBATCH and must precede all executable commands. On general-purpose ( GP) clusters this job reserves 1 core and 256MB of memory for 15 minutes. 12.5 Job hangs / no output / incomplete output.12.4 Jobs inherit environment variables.12.2 Cancellation of jobs with dependency conditions which cannot be met.12.1 Avoid hidden characters in job scripts.9 Resubmitting jobs for long running computations.
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