Cloud Scheduler Use Cases

The following use cases represent the basic functionality of the cloud scheduler - that is, the following tasks are those that will be regularly performed by the cloud scheduler. These use cases have been created to create abstract guidelines for the cloud scheduler development to follow. More technical, detailed information regarding the implementation of these steps can be found in the Cloud Scheduler Design document.

Job Arrival / VM Scheduling Case

The basic sequence that the cloud scheduler will perform on the arrival and detection of a job (as submitted to a job scheduler, currently a condor job pool) is as follows:

  • The job scheduler receives a job, job_X, that requires a X_VM type of virtual machine.
  • The cloud scheduler pulls the job scheduler queue and detects the newly submitted job_X.
  • The cloud scheduler then finds a copy of X_VM (in an image repoistory, or as specified by location in the job_X's job description file).
  • The cloud scheduler asks a registry service (the cloud MDS) for the current status of cloud resources, building an internal representation of cloud resources.
  • The cloud scheduler then searches these resources for a cluster that supports job_X's VM requirements (also specified in the job description file).
  • The cloud scheduler than sends provisioning instructions (create commands via Nimbus and the workspace-control program, currently) to a selected resource.
    • This creates a VM of type X_VM on the resource selected.
    • If this create call fails, the cloud scheduler will detect the failure and re-submit requests or choose new resources to submit requests to.

VM Expires / VM Termination Case

-- DuncanPenfoldBrown - 2009-06-12

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Topic revision: r1 - 2009-06-12 - dpb
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