Confluence Data Center Cluster Troubleshooting
Confluence Data Center is a clustered solution that is available from Confluence 5.6. If your cluster is running Confluence 5.4 or earlier, refer to Confluence Cluster Issues as there are some significant differences to the underlying clustering technology.
Confluence Data Center - a general overview of Data Center
Confluence Data Center Technical Overview - a more technical overview including Data Center works and the infrastructure you'll need to achieve performance at scale and high availability.
Data Center Troubleshooting - a good first port of call for troubleshooting information for Confluence Data Center.
Data Center Articles
Cluster Edition Articles