Deploying a Cluster - Mastering Apache Cassandra - page 197

Ec2Snitch treats the region name as the data center name and availability zone as the
rack name. EC2Snitch does not work across AWS regions. Therefore, effectively,
Ec2Snitch is the same as a single data center setup. If one of your nodes is in us-
east-1a and another in us-east-1b , it means that you have two nodes in a data cen-
ter named us-east in two racks, 1a and 1b .
EC2MultiRegionSnitch
Ec2Snitch does not work well if you decide to keep nodes across different EC2 re-
gions. The reason being EC2Snitch uses private IPs, which will not work across re-
gions (but does work across availability zones in a region).
If your cluster spans multiple regions, you should use EC2MultiRegionSnitch .
Note
EC2 users
If you plan to distribute nodes in different regions, there is more than just a proper snitch
that is needed to make nodes successfully communicate with each other. You need to
change the following configurations:
• broadcast_address : This should be the public IP or DNS of the node.
• listen_address : This should be set to a private IP or DNS. But if not set, the
hostname on EC2 is generally derived from the private IP, which is fine.
• endpoint_snitch : This should be set to EC2MultiRegionSnitch .
• storage_port : The default port number 7000 is fine, but remember to open
this port in the security group that holds Cassandra instances.