cassandra-rackdc.properties file

cassandra-rackdc.properties

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

The GossipingPropertyFileSnitch, Ec2Snitch, and Ec2MultiRegionSnitch use the configuration file to determine which datacenters and racks nodes belong to. They inform the database about the network topology to route requests efficiently and distribute replicas evenly. Settings for this file depend on the type of snitch:

This topic also includes instructions for migrating from the PropertyFileSnitch to the GossipingPropertyFileSnitch.

GossipingPropertyFileSnitch

This snitch is recommended for production. It uses rack and datacenter information for the local node defined in the cassandra-rackdc.properties file and propagates this information to other nodes via gossip.

To configure a node to use GossipingPropertyFileSnitch, edit the cassandra-rackdc.properties file as follows:

Define the datacenter and rack that include this node. The default settings:
```
dc=DC1
rack=RAC1
```
Note: datacenter and rack names are case-sensitive. For examples, see Initializing a single datacenter per workload type and Initializing multiple datacenters per workload type.
To save bandwidth, add the prefer_local=true option. This option tells DataStax Distribution of Apache Cassandra™ (DDAC) to use the local IP address when communication is not across different datacenters.

Migrating from the PropertyFileSnitch to the GossipingPropertyFileSnitch

To allow migration from the PropertyFileSnitch, the GossipingPropertyFileSnitch uses the cassandra-topology.properties file when present. Delete the file after the migration is complete. For more information about migration, see Switching snitches.

Note: 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.