Apache Cassandra™ 2.0

Replacing a dead node

Steps to replace a node that has died for some reason, such as hardware failure.

You must prepare and start the replacement node, integrate it into the cluster, and then remove the dead node. If the node is a seed node, see Replacing a dead seed node.

Procedure

  1. Confirm that the node is dead using nodetool status:

    The nodetool command shows a down status for the dead node (DN):

  2. Note the Address of the dead node; it is used in step 5.
  3. Install Cassandra on the new node, but do not start Cassandra.

    If you used the Debian/Ubuntu install, Cassandra starts automatically and you must and stop the node and clear the data.

  4. Set the following properties in the cassandra.yaml and, depending on the snitch, the cassandra-topology.properties or cassandra-rackdc.properties configuration files:
    • auto_bootstrap - If this option has been set to false, you must set it to true. This option is not listed in the default cassandra.yaml configuration file and defaults to true.
    • cluster_name - The name of the cluster the new node is joining.
    • listen_address/broadcast_address - May usually be left blank. Otherwise, use IP address or host name that other Cassandra nodes use to connect to the new node.
    • endpoint_snitch - The snitch Cassandra uses for locating nodes and routing requests.
    • num_tokens - The number of vnodes to assign to the node. If the hardware capabilities vary among the nodes in your cluster, you can assign a proportional number of vnodes to the larger machines.
    • seed_provider - The -seeds list in this setting determines which nodes the new node should contact to learn about the cluster and establish the gossip process.
      Note: Seed nodes cannot bootstrap. Make sure the new node is not listed in the -seeds list.
    • Change any other non-default settings you have made to your existing cluster in the cassandra.yaml file and cassandra-topology.properties or cassandra-rackdc.properties files. Use the diff command to find and merge (by head) any differences between existing and new nodes.
  5. Start the replacement node with the replace_address option:
    • Packaged installs: Add the following option to /usr/share/cassandra/cassandra-env.sh file:
      JVM_OPTS="$JVM_OPTS -Dcassandra.replace_address=address_of_dead_node
    • Tarball installs: Start Cassandra with this option:
      $ sudo bin/cassandra -Dcassandra.replace_address=address_of_dead_node
  6. If using a packaged install, after the new node finishes bootstrapping, remove the option you added in step 5.

What's next

Remove the old node's IP address from the cassandra-topology.properties or cassandra-rackdc.properties file

CAUTION:
Wait at least 72 hours to ensure that old node information is removed from gossip. If removed from the property file too soon, problems may result.
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