Answers to the Quiz

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OpenStack Services and Application Workloads

  1. Which of the following OpenStack services are required by a standalone application, which you will install inside a VM only because it is incompatible with your personal workstation, and you need it for only a short period of time?

    • Identity (Keystone)
      Incorrect: The application and its VM do not need to authenticate to nor discover OpenStack services. Only you (the Operator) user has this need.

    • Compute (Nova)
      Correct: Nova manages VMs on OpenStack clusters.

    • Block Storage (Cinder)
      Incorrect: The requirements tell nothing about the need to store data longer than the life of the VM or for the need to preserve data in case of failures.

    • Networking (Neutron)
      Incorrect: The requirements do not state a need for connectivity to other VMs or servers.

    • Image (Glance)
      Incorrect: You (the Operator user) and OpenStack Nova need an operating system to boot your VM before you can install your standalone application. But the application itself does not need Glance to run.

  2. Which of the following OpenStack services are required by a database server whose data is expected to be recoverable after catastrophic events such as hardware failures of a compute server?

    • Identity (Keystone)
      Incorrect: The database application does not invoke OpenStack APIs.

    • Compute (Nova)
      Correct: To run a server, you need Nova.

    • Block Storage (Cinder)
      Correct: Without Nova volumes, data from the database server would be stored only on its compute node.

    • Networking (Neutron)
      Incorrect: The requirements did not state this is a client/server database.

    • Image (Glance)
      Incorrect: The database application does not need Glance to run.

  3. Which of the following OpenStack services are required by a web application, which you require to easily deploy into multiple OpenStack clusters, in different countries your company has data centers?

    • Identity (Keystone)
      Incorrect: The web application does not invoke OpenStack APIs.

    • Compute (Nova)
      Correct: To run an application, you need Nova.

    • Block Storage (Cinder)
      Incorrect: The requirements do not state where and how the web application stores its data. If all data from the application is stored in a database, running in another VM, then the application VM could be easily recreated from its Glance image. But ask about possible requirements for long-term storage of logs and how the application handles it. You might need Cinder for that.

    • Networking (Neutron)
      Correct: It is a web application, that requires network connectivity from web browsers on end-user computers or smartphones.

    • Image (Glance)
      Correct: The easiest way of replicating the application VM in multiple data centers is creating a custom Glance image and copying that image to all clusters.

  4. Which of the following OpenStack services are required by a monitoring application that collects performance metrics from OpenStack clusters, services, and compute nodes? The history of metrics and alerts, stored on the application VM, must be persistent because it will be input to capacity planning.

    • Identity (Keystone)
      Correct: The monitoring application invokes OpenStack APIs.

    • Compute (Nova)
      Correct: To run an application, you need Nova.

    • Block Storage (Cinder)
      Correct: The application stores data on its local disk which must be persistent.

    • Networking (Neutron)
      Correct: To invoke OpenStack APIs, the application needs network connectivity.

    • Image (Glance)
      Incorrect: The requirements do not state if the application is a custom, single server, or a set of servers replicated in multiple data centers.