Decommissioning a Node

Use the following procedure to remove a node and uninstall the MapR software. This procedure detaches the node from the cluster and removes the MapR packages, log files, and configuration files, but does not format the disks.


Before Decommissioning a Node, make sure any data on the node is replicated and any needed services are running elsewhere. If the node you are decommissioning runs a critical service such as CLDB or ZooKeeper, verify that enough instances of that service are running on other nodes in the cluster. See Planning the Cluster for recommendations on service assignment to nodes.

Complete the following steps to permanently decommission a node:
  1. Drain the node of data by moving the node to the /decommissioned physical topology. All the data on a node in the /decommissioned topology is migrated to volumes and nodes in the data topology.
  2. Run the following command to check if a given volume is present on the node:
    maprcli dump volumenodes -volumename <volume> -json | grep <ip:port>
    Note: Run this command for each non-local volume in your cluster to verify that the node being decommissioned is not storing any volume data.
  3. Change to the root user (or use sudo for the following commands).
  4. If ZooKeeper is installed on the node, stop it: service mapr-zookeeper stop
  5. Determine which MapR packages are installed on the node:
    • dpkg --list | grep mapr (Ubuntu)
    • rpm -qa | grep mapr (Red Hat or CentOS)
  6. Remove the packages by issuing the appropriate command for the operating system, followed by the list of services. Examples:
    • apt-get purge mapr-core mapr-cldb mapr-fileserver (Ubuntu)
    • yum erase mapr-core mapr-cldb mapr-fileserver (Red Hat or CentOS)
  7. Remove the /opt/mapr directory to remove any instances of hostid, hostname, zkdata, and zookeeper left behind by the package manager.
  8. Remove any MapR cores in the /opt/cores directory.
  9. f the node you have decommissioned is a CLDB node or a ZooKeeper node, then run on all other nodes in the cluster. See Configuring the Node.
    Warning: If you are using Ganglia, restart all gmeta and gmon daemons in the cluster.