Note: This post has been updated to reflect the changes in the queueing system after the software upgrade of Beskow in June, 2019.
Our supercomputer clusters at PDC, equipped with thousands of multi-core processors, can be used to solve large scientific/engineering problems. Because of their much higher performance compared to desktop computers or workstations, supercomputer clusters are also called high performance computing (HPC) clusters. Common application fields of HPC clusters include machine learning, galaxy simulation, climate modelling, bioinformatics, computational physics, quantum chemistry, etc.
Building an HPC cluster demands sophisticated technologies and hardware, but fortunately a regular HPC user doesn’t have to worry too much about that. As an HPC user you can submit jobs that request the compute nodes (physical groups of processors) to do the calculations/simulations you want. But note that you are not the only user of an HPC cluster, there are typically many users using the cluster for the same time period and all of them will be submitting their own jobs. You may have realized by now that there needs to be some soft of queueing system that organizes the jobs and distributes them to the compute nodes. This post will briefly introduce SLURM, which is used in all PDC clusters and is the most widely used workload manager for HPC clusters.
What is SLURM?
SLURM, or Simple Linux Utility for Resource Management, is an open-source cluster management and job scheduling system. It provides three key functions
- Allocation of resources (compute nodes) to users’ jobs
- Framework for starting/executing/monitoring jobs
- Queue management to avoid resource contention
In other words, SLURM oversees all the resources in the whole HPC cluster. Users then send their jobs (requests to run calculations/simulations) to SLURM for later execution. SLURM will keep all the submitted jobs in a queue and decide what priorities the jobs have and how the jobs are distributed to the compute nodes. SLURM provides a series of useful commands for the user which we will now go through.
