When we have schedule maintenance on the cluster, an announcement will go out and indicate the date/time that this is scheduled to start.

All jobs currently running on the cluster are allowed to finish, and we can aspect further jobs if Slurm can complete them before the maintenance starts.

Be conscious of: If an announcement goes out on a Monday that maintenance is to start on the following Friday, there is only a window of four days that any new job must complete within.

If you submit a job with a wall time of seven days, then this can not and will not be started since it can not complete before Friday.

You job will be accepted by Slurm, queued, have a status of pending, and automatically started once maintenance is completed and Slurm is restarted.

Remember: By default you must define the project (account) you’re using and a walltime.

[]$ salloc
salloc: error: You didn't specify a project account (-A,--account). Please open a ticket at arcc-help@uwyo.edu for help.
salloc: error: Job submit/allocate failed: Invalid account or account/partition combination specified

[]$ salloc -A <project-name>
salloc: error: You didn't specify a walltime (-t, --time=) for the job. Please open a ticket at arcc-help@uwyo.edu for help.
salloc: error: Job submit/allocate failed: Requested time limit is invalid (missing or exceeds some limit)

[]$ salloc -t 10:00
salloc: error: You didn't specify a project account (-A,--account). Please open a ticket at arcc-help@uwyo.edu for help.
salloc: error: Job submit/allocate failed: Invalid account or account/partition combination specified

# The bare minimum:
[]$ salloc -A <project-name> -t 10:00
salloc: Granted job allocation 1250349
salloc: Nodes mbcpu-025 are ready for job

If you need to explicitly request a partition, the name must be correct:

# Corrected:
[]$ salloc -A <project-name> -t 10:00 --partition=mb-l40s
salloc: Pending job allocation 1250907
salloc: job 1250907 queued and waiting for resources
salloc: job 1250907 has been allocated resources
salloc: Granted job allocation 1250907
salloc: Nodes mbl40s-001 are ready for job

Timeouts aren’t errors as such, just that the time you requested was not long enough to compete the computation.

Do not request 7 days just because you can!

Wall time is considered when Slurm tries to allocate your job.

A job is more likely to be back filled (slotted onto the cluster) in busy times than pending jobs will longer wall times.

ARCC can provide users with wall times longer than 7 days.

Please contact use, but we require that you can demonstrate that you job can not be optimized, for example:

• Can it run faster by using more cores, or even multiple nodes?

• Can it utilize GPUs?

• Can the job actually be divided up into sections that can be run concurrently across multiple jobs?

ARCC can provide assistance with trying to understand if a job can be optimized.

This is caused because you’re trying to request a configuration that isn’t available, or requires more details: For example:

[]$ salloc -A <project-name> -t 10:00 --gres=gpu:1
salloc: error: Job submit/allocate failed: Requested node configuration is not available
salloc: Job allocation 1253677 has been revoked.

[]$ salloc -A <project-name> -t 10:00 --gres=gpu:1 --partition=mb-a30
salloc: Granted job allocation 1253691
salloc: Nodes mba30-001 are ready for job

Segmentation faults are typically caused by an application trying to access memory outside what has been allocated to the job.

Basically, you job is out of memory of what it requested.

Resolved: Request more memory using either the mem or mem-per-cpu .

• As discussed in the Intro to HPC workshop, we have a Condominium Model where if your job is running an a compute node that is part of another project’s hardware investment, your job can be preempted.

• Your job will be stopped and automatically re-queued and when resources come available on the cluster, it will be restarted.

• Further details can be found on our Slurm and Preemption page and how to use the non-investor partition to prevent this from happening.

When I run pestat, it appears that my job is one of many on a particular compute node.

[]$ pestat -n mbl40s-001
Select only nodes in hostlist=mbl40s-001
Hostname         Partition     Node Num_CPU  CPUload  Memsize  Freemem  Joblist
                              State Use/Tot  (15min)     (MB)     (MB)  JobID(JobArrayID) User ...
mbl40s-001         mb-l40s     mix   64  96   55.62*   765525   310618  1480439 hbalantr 1440260 vvarenth

As discussed in the Intro to HPC workshop when talking about Compute Nodes this is perfectly acceptable and one of the tasks that Slurm manages.

Remember: All jobs are independent and do not affect anyone else.