In this WebLogic Server domain topology, there is a WebLogic Administration server and a Coherence cluster. The Coherence cluster contains two WebLogic Server clusters. The first WebLogic Server cluster is storage-disabled (the WebLogic Server Coherence client tier). The second WebLogic Server cluster contains two managed Coherence servers with storage enabled (WebLogic Server Coherence server tier). In case of failover, one server can be used as backup for the other.