MidoNet uses Apache Cassandra to store flow state information, for example NAT bindings, connection tracking information, and to support VM migration.

While, MidoNet leverages Cassandra’s durability, fault tolerance, timed expirations, and low-latency read/writes, it only uses Cassandra as a backup rather than the primary datasource.

 Necessary software

Cassandra requires a Java Runtime Environment (JRE).

We recommend OpenJDK 7, which is available as part of most Linux distributions or can be installed using the official installation guide (go to and navigate to the installing information).

 Fault-tolerant configuration guidelines

The minimum recommended Cassandra setup is a three-node cluster with a replication factor (N) of three.

The MidoNet Agent (Midolman) uses QUORUM as a consistency policy of N/2 + 1, which translates to two in the suggested setup.

 Accessibility considerations

Cassandra uses two IP addresses: one for intra-cluster communication (the listen_address parameter) and another one for client connections via remote procedure calls (RPC) (rpc_address).

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