In eXo Platform 4, Clustering mode is temporarily not available for Tomcat. The whole content of this chapter is for JBoss only. eXo Platform is trying best to support Clustering mode for Tomcat soon.
Clustering allows eXo Platform users to run various portal instances on several parallel servers which are also called nodes. The load is distributed across different servers, so the portal is still accessible via other cluster nodes in case of any failed servers. Thanks to adding more nodes to the cluster, eXo Platform's performance can be much improved. In this chapter, you will see the following topics:
Information and characteristics of eXo Platform cluster, and steps to do a typical setup.
How to enable local JCR index.
How to set up load balancing using Apache mod_jk.
How to configure Job Persistence for Quartz Scheduler.
Common questions and answers that are useful for administrators when doing a clustering on eXo Platform.
A cluster is a set of nodes which are managed together and participate in the workload management. Installing eXo Platform in the cluster mode is considered in the following main cases:
Load Balancing: when a single server node is not enough for handling the load.
High Availability: if one of nodes is failed, the rest of nodes in the cluster can assume the workload of the system. It means that no access is interrupted.
These characteristics should be handled by the overall architecture of your system. The Load Balancing is typically achieved by a front server or device that distributes the request to the cluster nodes. Also, the High Availability on the data layer can be typically achieved using the native replication implemented by Relation Database Management System (RDBMS) or Shared File Systems, such as SAN and NAS.