7.1. FAQ

Q. Can you update a cluster with a Snapshot ID, ie. update a cluster to use the /shared/build pre-installed software?

A. No. An existing cluster can not be updated with a Snapshot ID, solution is to delete the cluster and re-create it. see error:

pcluster update-cluster --region us-east-1 --cluster-name cmaq --cluster-configuration c5n-18xlarge.ebs_unencrypted.fsx_import.yaml

Output:

{
  "message": "Update failure",
  "updateValidationErrors": [
    {
      "parameter": "SharedStorage[ebs-shared].EbsSettings.SnapshotId",
      "requestedValue": "snap-065979e115804972e",
      "message": "Update actions are not currently supported for the 'SnapshotId' parameter. Remove the parameter 'SnapshotId'. If you need this change, please consider creating a new cluster instead of updating the existing one."
    }
  ],
  "changeSet": [
    {
      "parameter": "SharedStorage[ebs-shared].EbsSettings.SnapshotId",
      "requestedValue": "snap-065979e115804972e"
    }
  ]
}

Q. How do you figure out why a job isn’t successfully running in the slurm queue?

A. Check the logs available in the following link

Pcluster Troubleshooting

vi /var/log/parallelcluster/slurm_resume.log

Output:

2022-03-23 21:04:23,600 - [slurm_plugin.instance_manager:_launch_ec2_instances] - ERROR - Failed RunInstances request: 0c6422af-c300-4fe6-b942-2b7923f7b362
2022-03-23 21:04:23,600 - [slurm_plugin.instance_manager:add_instances_for_nodes] - ERROR - Encountered exception when launching instances for nodes (x3) ['queue1-dy-compute-resource-1-4', 'queue1-dy-compute-resource-1-5', 'queue1-dy-compute-resource-1-6']: An error occurred (InsufficientInstanceCapacity) when calling the RunInstances operation (reached max retries: 1): We currently do not have sufficient c5n.18xlarge capacity in the Availability Zone you requested (us-east-1a). Our system will be working on provisioning additional capacity. You can currently get c5n.18xlarge capacity by not specifying an Availability Zone in your request or choosing us-east-1b, us-east-1c, us-east-1d, us-east-1f.

Q. How do I determine what node(s) the job is running on?

A. echo $SLURM_JOB_NODELIST

Slurm Environment Variables

Q. I see other tutorials that use a configure file instead of a yaml file to create the cluster. Can I use this instead?

A. No, you must convert the text based config file to a yaml file to use with the Parallel Cluster CLI 3.+ version used in this tutorial. An example of this type of tutorial is < a href=”https://aws.amazon.com/blogs/compute/fire-dynamics-simulation-cfd-workflow-using-aws-parallelcluster-elastic-fabric-adapter-amazon-fsx-for-lustre-and-nice-dcv/”> Fire Dynamics Simulation CFD workflow using AWS ParallelCluster, Elastic Fabric Adapter, Amazon FSx for Lustre and NICE DCV You can try to use the v2 to v3 converter, see more: moving from v2 to v3

Q. If I find an issue, or need help with this CMAQ ParallelCluster Tutorial what do I do?

A. Please file an issue using github.

Submit Github Issue for help with documentation

Please indicate the issue you are having, and include a link from the read the doc section that you are referring to. The tutorial documentation has an edit icon in the upper right corner of each page. You can click on that, and github will fork the repo and allow you to edit the page. After you have made the edits, you can submit a pull request, and then include the link to the pull request in the github issue.