1. Introduction  
2. Uses and Architecture of High-Availability Clusters  
2.1. Key Concepts and Terminology  
2.2. Enterprise Application Layers  
2.3. HAC Architecture  
3. Taxonomy of High-Availability Clusters  
3.1. A: Deployment Pattern  
3.2. B: Application Areas  
3.3. C: Type of Cluster  
3.4. D: Topology  
3.5. E: Cluster Management  
3.6. F: Failure Detection and Recovery  
3.7. G: Consistency and Integrity  
3.8. H: Data Synchronization  
4. Survey of High-Availability Clusters  
4.1. Selection of HACs for the Survey  
4.2. HAC Analysis Methodology  
4.3. HAC Survey Results  
4.4. Analysis of the Survey Results  
5. Future Directions  
5.1. Limitations  
5.2. Challenges  
5.3. Opportunities  
6. Conclusions