How to cluster Tomcat servers

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A cluster is two or more servers that provide the same services. For example, a cluster may have two Tomcat application servers. If one of the Tomcat server fails, the other server in the cluster can continue to serve web requests.


On both Tomcat servers, add <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" /> to the <Engine> or <Host> container in your $CATALINA_HOME/conf/server.xml file.

<Engine name="Catalina" defaultHost="localhost">
  <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" />
   . . .


To test this, shutdown server 1 and ensure server 2 continues to serve requests.

[john.doe@server1 ~]# $CATALINA_HOME/bin/


Use the Tomcat manual for more details on clustering.

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