In cluster deployments, Cassandra clustering provides redundant storage of SIP device data on Avaya Aura® Device Services nodes. To further improve resiliency, you can assign each node to a specific Cassandra datacenter. A datacenter is a logical grouping of Avaya Aura® Device Services nodes within the cluster. When you use multiple datacenters, the Cassandra database is replicated on the nodes as follows:

• Each Cassandra datacenter configured in your deployment has its own replica of the Cassandra database.

• Within a Cassandra datacenter, the database is replicated on multiple nodes. The exact number of copies depends on the number of nodes in the datacenter.

Avaya Aura® Device Services automatically configures and maintains the replication settings, such as the replication factor, for each datacenter.

By default, all cluster nodes belong to the default Cassandra datacenter, which has the dc1 name. To assign a node to another datacenter, specify the datacenter name when installing the node or at any time after installation. If you do not select a datacenter during installation, Avaya Aura® Device Services assigns the node to the default datacenter. If required, you can move nodes between datacenters.

By default, Avaya Aura® Device Services synchronizes the data between the databases weekly. You can schedule the synchronization on a specific day of the week or disable the synchronization.

Recommendations for configuring Cassandra clustering

Avaya recommends that you:

• Use two Cassandra datacenters in your deployment.

  You can configure more than two datacenters, but it might not provide additional redundancy compared to the two datacenters setup.

• Distribute Avaya Aura® Device Services nodes evenly between the Cassandra datacenters to balance the load on each datacenter.

• Configure an additional seed node so that:

  • The primary seed node belongs to one datacenter.

  • The additional seed node belongs to another datacenter.

  This approach improves bootstrapping the gossip process for new nodes joining the cluster. When you add a new node to a datacenter, this node communicates with the seed node of the datacenter instead of the main seed node of the cluster.

• In a geographically distributed deployment, assign Avaya Aura® Device Services nodes to Cassandra datacenters based on node location. Thus, you minimize the network latency in internode communications.

Considerations

If you upgrade to Release 10.2.x from a previous release, all nodes in your deployment belong to the default dc1 datacenter. You can configure datacenters as appropriate on the Clustering configuration page of the configuration utility. For more information about re-assigning nodes to datacenters, see Chapter Cassandra clustering configuration on Avaya Aura® Device Services in Administering Avaya Aura® Device Services.