Large Memory Jobs on BlueBEAR

Each of BlueBEAR’s Ice Lake nodes (introduced autumn 2021) have approximately 490GB memory (RAM) available for running jobs and are therefore suitable for tasks that require a large amounts of memory. The simplest way to request a large amount of memory is to include the following #SBATCH headers in your job script:

#SBATCH --nodes=1
#SBATCH --mem=244G

Efficient Use

To ensure that BlueBEAR’s resources are used efficiently we prefer that resource requests work on the basis of quarter-node slices, which means that other jobs can run on the same node, concurrently with a larger-memory job. Please therefore request --mem in multiples of 122G.

Another solution is to use the --mem-per-cpu Slurm option, and then scale using --ntasks. For example:

#SBATCH --nodes=1
#SBATCH --mem-per-cpu=6750M
#SBATCH --ntasks=54

In the above example we’re specifying 54 cores (or three quarters of the available 72 cores) to get 365580M memory. Another user (or another of your jobs) could then ask for 18 cores at 6750M each, and get the remaining 121500M.

BlueBEAR Large Memory Service (a.k.a. bblargemem QOS)

Due to the changes in BlueBEAR’s topology as outlined above, the bblargemem QOS has been retired as the higher-memory Ice Lake nodes are available via the standard QOSes.