This is documentation for MapR Version 5.0. You can also refer to MapR documentation for the latest release.

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To re-purpose machines, you may want to remove nodes and uninstall MapR software.

Removing Nodes from a Cluster

To remove nodes from a cluster: first uninstall the desired nodes, then run configure.sh on the remaining nodes. Finally, if you are using Ganglia, restart all gmeta and gmon daemons in the cluster.

To uninstall a node:

On each node you want to uninstall, perform the following steps:

Before you start, 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.

Run the following command to check if a given volume is present on the node:

Run this command for each non-local volume in your cluster to verify that the node being decommissioned is not storing any volume data.

  1. Change to the root user (or use sudo for the following commands).
  2. Stop Warden:
    service mapr-warden stop
  3. If ZooKeeper is installed on the node, stop it:
    service mapr-zookeeper stop
  4. Determine which MapR packages are installed on the node:
    • dpkg --list | grep mapr (Ubuntu)
    • rpm -qa | grep mapr (Red Hat or CentOS)
  5. 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)
  6. Remove the /opt/mapr directory to remove any instances of hostidhostnamezkdata, and zookeeper left behind by the package manager.
  7. Remove any MapR cores in the /opt/cores directory.
  8. If the node you have decommissioned is a CLDB node or a ZooKeeper node, then run configure.sh on all other nodes in the cluster (see Configuring the Node).

To reconfigure the cluster:

The script configure.sh configures a node to be part of a MapR cluster, or modifies services running on an existing node in the cluster. The script creates (or updates) configuration files related to the cluster and the services running on the node.

Before you run configure.sh, make sure you have a list of the hostnames of the CLDB and ZooKeeper nodes. You can optionally specify the ports for the CLDB and ZooKeeper nodes as well. The default ports are:

Service
Default Port #
CLDB7222
ZooKeeper5181

The script configure.sh takes an optional cluster name and log file, and comma-separated lists of CLDB and ZooKeeper host names or IP addresses (and optionally ports), using the following syntax:

/opt/mapr/server/configure.sh -C <host>[:<port>][,<host>[:<port>]...] -Z <host>[:<port>][,<host>[:<port>]...] [-L <logfile>][-N <cluster name>]
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Each time you specify the -Z <host>[:<port>] option, you must use the same order for the ZooKeeper node list. If you change the order for any node, the ZooKeeper leader election process will fail.

Example:

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If you are using Ganglia, restart all gmeta and gmon daemons in the cluster. See Ganglia.

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