Configuring and Initializing a DataStax Enterprise Cluster¶

Generating Tokens¶

Tokens are used to assign a range of data to a particular node. Assuming you are using the RandomPartitioner, this approach will ensure even data distribution.

1. Create a new file for your token generator program:

   vi tokengentool
   

2. Paste the following Python program into this file:

   #! /usr/bin/python
   import sys
   if (len(sys.argv) > 1):
       num=int(sys.argv[1])
   else:
       num=int(raw_input("How many nodes are in your cluster? "))
   for i in range(0, num):
       print 'node %d: %d' % (i, (i*(2**127)/num))
   

3. Save and close the file and make it executable:

   chmod +x tokengentool
   

4. Run the script:

   ./tokengentool
   

5. When prompted, enter the total number of nodes in your cluster:

   How many nodes are in your cluster? 6
   node 0: 0
   node 1: 28356863910078205288614550619314017621
   node 2: 56713727820156410577229101238628035242
   node 3: 85070591730234615865843651857942052864
   node 4: 113427455640312821154458202477256070485
   node 5: 141784319550391026443072753096570088106
   

6. On each node, edit the cassandra.yaml file and enter its corresponding token value in the initial_token property.

Configuring Firewall Port Access¶

If you have a firewall running on the nodes in your Cassandra or DataStax Enterprise cluster, you must open up the following ports to allow communication between the nodes, including certain Cassandra ports. If this isn’t done, when you start Cassandra (or Hadoop in DataStax Enterprise) on a node, the node will act as a standalone database server rather than joining the database cluster.

Starting DataStax Enterprise as a Stand-Alone Process¶

If running a mixed-workload cluster, determine which nodes to start as Cassandra nodes and which nodes to start as Analytics nodes. Begin with the seed nodes first - Analytics seed node, followed by the Cassandra seed node - then start the remaining nodes in the cluster one at a time.

On an Analytics node:

dse cassandra -t

On a Cassandra node:

dse cassandra

Starting DataStax Enterprise as a Service¶

Packaged installations provide startup scripts in /etc/init.d for starting DSE as a service. Before starting DSE as a service on an Analytics node, you must first configure the service to start the Hadoop Job Tracker and Task Tracker services as well.

1. Create the file /etc/default/dse, and add the following line as the contents of this file:

   HADOOP_ENABLED=1
   

2. Start the DSE service:

   sudo service dse start