Initializing a multiple node cluster (single datacenter)

A deployment scenario for an Apache Cassandra cluster with a single datacenter.

1. Suppose you install Cassandra on these nodes:

   node0 110.82.155.0 (seed1)
   node1 110.82.155.1
   node2 110.82.155.2
   node3 110.82.156.3 (seed2)
   node4 110.82.156.4
   node5 110.82.156.5

   Note: It is a best practice to have more than one seed node per datacenter.
2. If you have a firewall running in your cluster, you must open certain ports for communication between the nodes. See Configuring firewall port access.
3. If Cassandra is running, you must stop the server and clear the data:

   Doing this removes the default cluster_name (Test Cluster) from the system table. All nodes must use the same cluster name.

   Package installations:

   1. Stop Cassandra:

      sudo service cassandra stop #Stops Cassandra

   2. Clear the data:

      sudo rm -rf /var/lib/cassandra/*

   Tarball installations:

   1. Stop Cassandra:

      ps auwx | grep cassandra

      sudo kill pid

   2. Clear the data:

      sudo rm -rf install_location/data/*

4. Set the properties in the cassandra.yaml file for each node:
   Note: After making any changes in the cassandra.yaml file, you must restart the node for the changes to take effect.

   Properties to set:

   • cluster_name:
   • num_tokens: recommended value: 256
   • -seeds: internal IP address of each seed node

     In new clusters. Seed nodes don't perform bootstrap (the process of a new node joining an existing cluster.)

   • listen_address:

     If the node is a seed node, this address must match an IP address in the seeds list. Otherwise, gossip communication fails because it doesn't know that it is a seed.

     If not set, Cassandra asks the system for the local address, the one associated with its hostname. In some cases Cassandra doesn't produce the correct address and you must specify the listen_address.

   • rpc_address:listen address for client connections
   • endpoint_snitch: name of snitch (See endpoint_snitch.) If you are changing snitches, see Switching snitches.

   Note: If the nodes in the cluster are identical in terms of disk layout, shared libraries, and so on, you can use the same cassandra.yaml file on all of them.

   Example:

   cluster_name: 'MyCassandraCluster'
   num_tokens: 256
   seed_provider:
     - class_name: org.apache.cassandra.locator.SimpleSeedProvider
       parameters:
            - seeds: "110.82.155.0,110.82.155.3"
   listen_address:
   rpc_address: 0.0.0.0
   endpoint_snitch: GossipingPropertyFileSnitch

   If rpc_address is set to a wildcard address (0.0.0.0), then broadcast_rpc_address must be set, or the service won't even start.
5. In the cassandra-rackdc.properties file, assign the datacenter and rack names you determined in the Prerequisites. For example:

   # indicate the rack and dc for this node
   dc=DC1
   rack=RAC1

6. The GossipingPropertyFileSnitch always loads cassandra-topology.properties when that file is present. Remove the file from each node on any new cluster or any cluster migrated from the PropertyFileSnitch.
7. After you have installed and configured Cassandra on all nodes, DataStax recommends starting the seed nodes one at a time, and then starting the rest of the nodes.
   Note: If the node has restarted because of automatic restart, you must first stop the node and clear the directories, as described above.

   Package installations:

   sudo service cassandra start #Starts Cassandra

   Tarball installations:

   cd install_location

   bin/cassandra

8. To check that the ring is up and running, run:
   Package installations:

   nodetool status

   Tarball installations:

   cd install_location

   bin/nodetool status

   The output should list each node, and show its status as UN (Up Normal).

   

   The location of the cassandra.yaml file depends on the type of installation:

   Cassandra package installations	/etc/cassandra/cassandra.yaml
   Cassandra tarball installations	install_location/cassandra/conf/cassandra.yaml