PropertyFileSnitch

Determines the location of nodes by rack and data center.

This snitch determines proximity is determined by rack and data center. It uses a user-defined description of the network details located in the cassandra-topology.properties file. Use this snitch when your node IPs are not uniform or if you have complex replication grouping requirements. When using this snitch, you can define your data center names to be whatever you want. Make sure that the data center names you define correlate to the name of your data centers in your keyspace definition. Every node in the cluster should be described in the cassandra-topology.properties file, and this file should be exactly the same on every node in the cluster.

The location of the cassandra-topology.properties file depends on the type of installation:
  • Packaged installs: /etc/cassandra/cassandra-topology.properties
  • Tarball installs: install_location/conf/cassandra-topology.properties

Procedure

If you had non-uniform IPs and two physical data centers with two racks in each, and a third logical data center for replicating analytics data, the cassandra-topology.properties file might look like this:
Note: Data center and rack names are case-sensitive.
# Data Center One

175.56.12.105 =DC1:RAC1
175.50.13.200 =DC1:RAC1
175.54.35.197 =DC1:RAC1

120.53.24.101 =DC1:RAC2
120.55.16.200 =DC1:RAC2
120.57.102.103 =DC1:RAC2

# Data Center Two

110.56.12.120 =DC2:RAC1
110.50.13.201 =DC2:RAC1
110.54.35.184 =DC2:RAC1

50.33.23.120 =DC2:RAC2
50.45.14.220 =DC2:RAC2
50.17.10.203 =DC2:RAC2

# Analytics Replication Group

172.106.12.120 =DC3:RAC1
172.106.12.121 =DC3:RAC1
172.106.12.122 =DC3:RAC1

# default for unknown nodes default =DC3:RAC1