failover-to-ondemand.md

Slurm Failover from Spot to On-Demand

In AWS ParallelCluster you can setup a cluster with two queues, one for Spot pricing and one for On-demand. When a job fails, due to a spot reclaimation, you can automatically requeue that job to OnDemand.

To set that up, first create a cluster with a Spot and OnDemand queue:

- Name: od
    ComputeResources:
      - Name: c6i-od-c6i32xlarge
        MinCount: 0
        MaxCount: 4
        InstanceType: c6i.32xlarge
        Efa:
          Enabled: true
          GdrSupport: true
        DisableSimultaneousMultithreading: true
    Networking:
      SubnetIds:
        - subnet-846f1aff
      PlacementGroup:
        Enabled: true
  - Name: spot
    ComputeResources:
      - Name: c6i-spot-c6i32xlarge
        MaxCount: 4
        InstanceType: c6i.32xlarge
    Networking:
      SubnetIds:
        - subnet-846f1aff
    CapacityType: SPOT

Next submit your job like so:

$ sbatch -p spot --norequeue submit.sbatch
Submitted job with id 1
$ sbatch -p od -d afternotok:1 submit.sbatch
Submitted job with id 2

• --norequeue tells slurm to not requeue in the same queue as the first job.
• afternotok:1 tells slurm to only run the second job if the first one (job id 1) fails.