Ec2Snitch

Snitch for an Amazon EC2 deployment in a single region.

cassandra-rackdc.properties

  • The cassandra-rackdc.properties file is located in the installation_location/conf directory.

Use the Ec2Snitch for simple cluster deployments on Amazon EC2 where all nodes in the cluster are within a single region.

In EC2 deployments, the region name is treated as the datacenter name and availability zones are treated as racks within a datacenter. For example, if a node is in the us-east-1 region, us-east is the datacenter name and 1 is the rack location. (Racks are important for distributing replicas, but not for datacenter naming.) Because private IPs are used, this snitch does not work across multiple regions.

If you are using only a single datacenter, you do not need to specify any properties.

If you need multiple datacenters, set the dc_suffix options in the cassandra-rackdc.properties file. Any other lines are ignored.

For example, for each node within the us-east region, specify the datacenter in its cassandra-rackdc.properties file:
Note: datacenter names are case-sensitive.
  • node0

    dc_suffix=_1_cassandra

  • node1

    dc_suffix=_1_cassandra

  • node2

    dc_suffix=_1_cassandra

  • node3

    dc_suffix=_1_cassandra

  • node4

    dc_suffix=_2_cassandra

  • node5

    dc_suffix=_3_cassandra

This results in three datacenters for the region:
us-east_1_cassandra
us-east_2_cassandra
us-east_3_cassandra

Keyspace strategy options

When defining your keyspace strategy options, use the EC2 region name, such as ``us-east``, as your datacenter name.