Installing a Cluster - spectrum_platform - 23.1

Installing a cluster involves setting up one Spectrum Technology Platform server at a time.

It is recommend to have at least 3 nodes in a cluster. The smallest fault tolerant cluster is a cluster that can tolerate one lost server. This requires a minimum of three Core instances. Both a three-server cluster and a four-server cluster can tolerate a maximum of one lost server. It is recommended in order to tolerate two failed Core instances, you need to deploy a cluster of five Core instances.

Before you begin, install an appropriate load balancer. Follow the procedures described in the load balancer documentation when installing.

Note: The load balancer must be configured to allow encoded forward slashes. If the load balancer does not allow encoded forward slashes you may get HTTP 404 errors while using the cluster. For example, if you are using an Apache load balancer, you can configure it to allow encoded forward slashes by opening the httpd.conf file and specifying this property: AllowEncodedSlashes On. For other types of load balancers, refer to the load balancer documentation.

Once you have your load balancer installed, follow these steps to install nodes in the cluster.

1. Install Spectrum Technology Platform on each node in the cluster.
   For instructions, see Installing a New Server.
   Important: Do not start the server when the installation completes. You must complete the following steps before starting the server.
2. On each node, configure settings in the spectrum-container.properties file.
   1. Edit the properties in file SpectrumDirectory/server/conf/spectrum-container.properties, as described in Cluster Properties.
   2. Save and close the spectrum-container.properties file.
   3. Some modules have module-specific settings that you must configure to enable the module to work in a cluster.

      Module	Cluster Configuration Settings
      Context Graph	Context Graph models are stored on an external Neo4j Graph Database Server. For instructions about how to configure and connect to Neo4j Graph Database Server in a clustered configuration, see Installing a Cluster for Context Graph.

3. On each node, configure settings for Search Index.
   1. Open the file SpectrumDirectory/index/opensearch.template and scroll down to the Node Address section.
   2. Remove the hash character # to uncomment the following line:

      cluster.initial_master_nodes: ${seeds}

      Then edit it to specify the node names in the cluster:

      cluster.initial_master_nodes: node-1,node-2,node-3,...

      Important: This setting must be uncommented when you start the cluster for the first time.
   3. Insert the hash character # to comment out the following line:

      #discovery.type: single-node

4. Confirm the following settings on each node in the cluster.
   • SpectrumDirectory/repository/neo4j.template

     dbms.active_database=graphdb
     dbms.default_database=graphdb
     dbms.default_listen_address=0.0.0.0
     causal_clustering.discovery_advertised_address=${spectrum.agent.address}
     causal_clustering.enable_pre_voting=false
     dbms.routing.enabled=true
     dbms.routing.listen_address=0.0.0.0
     dbms.routing.advertised_address=${spectrum.agent.address}

5. Start each server in the cluster.
   Do not wait for one node to start before starting another node. All nodes must be started at the same time.
   For more information, see Starting a Cluster.