o be homogeneous, all nodes must deploy the same applications and be exact replicas.
  The <code>org.apache.catalina.ha.session.BackupManager</code> also replicates deltas but only to one backup node.
  The location of the backup node is known to all nodes in the cluster. It also supports heterogeneous deployments,
  so the manager knows at what locations the webapp is deployed.<br>
  We are planning to add more managers with even more sophisticated backup mechanism to support even larger clusters.
  Check 