Frequently Asked Questions

Frequently Asked Questions

Q. Can I install DC/OS on an already running Mesos cluster?

We recommend starting with a fresh cluster to ensure all defaults are set to expected values. This prevents unexpected conditions related to mismatched versions and configurations.

Q. What are the OS requirements of DC/OS?

See the system requirements.

Q. Does DC/OS install ZooKeeper, or can I use my own ZooKeeper quorum?

DC/OS runs its own ZooKeeper supervised by Exhibitor and systemd, but users are able to create their own ZooKeeper quorums as well. The ZooKeeper quorum installed by default will be available at master.mesos:[2181|2888|3888].

Q. Is it necessary to maintain a bootstrap node after the cluster is created?

If you specify an Exhibitor storage backend type other than exhibitor_storage_backend: static in your cluster configuration file, you must maintain the external storage for the lifetime of your cluster to facilitate leader elections. If your cluster is mission critical, you should harden your external storage by using S3 or running the bootstrap ZooKeeper as a quorum. Interruptions of service from the external storage can be tolerated, but permanent loss of state can lead to unexpected conditions.

Q. How to add Mesos attributes to nodes in order to use Marathon constraints?

In DC/OS, add the line MESOS_ATTRIBUTES=<key>:<value> to the file /var/lib/dcos/mesos-slave-common (it may need to be created) for each attribute you’d like to add. More information can be found via the Mesos doc.

Q. How do I gracefully shut down an agent?

  • _To gracefully kill an agent node’s Mesos process and allow systemd to restart it, use the following command. Note: If Auto Scaling Groups are in use, the node will be replaced automatically:

      sudo systemctl kill -s SIGUSR1 dcos-mesos-slave
    
  • For a public agent:

      sudo systemctl kill -s SIGUSR1 dcos-mesos-slave-public
    
  • To gracefully kill the process and prevent systemd from restarting it, add a stop command:

      sudo systemctl kill -s SIGUSR1 dcos-mesos-slave && sudo systemctl stop dcos-mesos-slave
    
  • For a public agent:

      sudo systemctl kill -s SIGUSR1 dcos-mesos-slave-public && sudo systemctl stop dcos-mesos-slave-public