SLURM is a resource manager and job scheduler for high-performance computing clusters. We use a job scheduler to ensure fair usage of the research-computing resources by all users, with hopes that no one user can monopolize the computing resources. Users who wish to use the cluster must "request" CPU time and possibly "queue" for resources.
Our SLURM is configured with the following job queues (also called "partitions" in SLURM):
"debug" is the default queue, which is useful for testing job parameters, program paths, etc. The run-time limit of the "debug" partition is 5 minutes, after which jobs are killed. The other partitions have no set time limit.
To see more information about the queue configuration, use sinfo -lNe.
$ sinfo -lNe Thu Aug 04 15:08:48 2022 NODELIST NODES PARTITION STATE CPUS S:C:T MEMORY TMP_DISK WEIGHT AVAIL_FE REASON compute03 1 highmem idle 8 2:4:1 322249 0 10 (null) none compute05 1 batch mixed 48 2:24:1 386500 0 10 (null) none compute06 1 batch mixed 64 2:32:1 257491 0 5 (null) none compute07 1 highmem idle 8 1:8:1 101956 0 5 (null) none hpc 1 debug* idle 4 1:4:1 128876 0 1 (null) none
The above tells you, for instance, that compute06 has 64 CPUs. And that a job sent to the "highmem" partition (a SLURM verb equivalent to "queue", as per the vocabulary in use with other schedulers, e.g. Sun Grid Engine), then it will end up being run on either compute03 or compute07.
How to get an interactive session, i.e. when you want to interact with a program (like R, etc) for a limited amount of time, making the scheduler aware that you are requesting/using resources on the cluster:
[aorth@hpc: ~]$ interactive salloc: Granted job allocation 1080 [aorth@compute05: ~]$
NB: interactive jobs have a time limit of 8 hours: if you need more, then you should write an sbatch script.
You can also open an interactive session on a specific node of the cluster by specifying it through the -w commandline argument:
[jbaka@hpc ~]$ interactive -w compute03 salloc: Granted job allocation 16349 [jbaka@compute03 ~]$
We are writing a SLURM script below. The parameters in its header request 4 CPUs for in the batch partition, and name our job "blastn". This name is only used internally by SLURM for reporting purposes. So let's go ahead and ceate a file blast.sbatch:
#!/usr/bin/bash -l #SBATCH -p batch #SBATCH -J blastn #SBATCH -n 4 # load the blast module module load blast/2.6.0+ # run the blast with 4 CPU threads (cores) blastn -query ~/data/sequences/drosoph_14_sequences.seq -db nt -num_threads 4
In the above, please DO NOT FORGET the '-l' option on the first ("sha-bang") line, as it is compulsory for correct interpretation of the module load commands.
We then submit the script with the sbatch command:
$ sbatch blast.sbatch Submitted batch job 1082
Users' home folders are mounted over the network (on "wingu"), so when you're on mammoth or taurus any time you write to the disk (ie job output) has to go round trip over the network.
Instead, you can use a local "scratch" folder on the compute nodes to alleviate this burden, for example:
#!/usr/bin/bash -l #SBATCH -p batch #SBATCH -J blastn #SBATCH -n 4 # load the blast module module load blast/2.2.30+ WORKDIR=/var/scratch/$USER/$SLURM_JOBID mkdir -p $WORKDIR echo "Using $WORKDIR on $SLURMD_NODENAME" echo # change to working directory on compute node cd $WORKDIR # run the blast with 4 CPU threads (cores) blastn -query ~/data/sequences/drosoph_14_sequences.seq -db nt -num_threads 4 -out blast.out
All output is directed to $WORKDIR/, which is the temporary folder on the compute node. See these slides from HPC Users Group #3 for more info.
squeue is the command to use in order to get information about the different jobs that are running on the cluster, waiting in a queue for resources to become available, or halted for some reason:
$ squeue JOBID PARTITION NAME USER ST TIME CPUS NODELIST(REASON) 746596 batch structure aorth R 5-15:27:10 1 compute06 746597 batch structure aorth R 5-13:49:37 1 compute06 746885 batch model-selection jjuma R 4-20:45:15 8 compute06 746998 batch interactive afeleke R 30:09 1 compute06 746999 batch blastp aorth R 7:20 6 compute05