High-Availability Clusters: A Taxonomy, Survey, and Future Directions

TL;DR

This paper provides a comprehensive overview of high-availability clusters, including their architecture, taxonomy, existing solutions, limitations, and future research directions for mission-critical enterprise applications.

Contribution

It introduces a detailed taxonomy of HACs, surveys current software solutions, and discusses future challenges and opportunities in high-availability clustering.

Findings

HACs are crucial for mission-critical application continuity.

Existing solutions have limitations in scalability and flexibility.

Future research should address automation and robustness.

Abstract

The delivery of key services in domains ranging from finance and manufacturing to healthcare and transportation is underpinned by a rapidly growing number of mission-critical enterprise applications. Ensuring the continuity of these complex applications requires the use of software-managed infrastructures called high-availability clusters (HACs). HACs employ sophisticated techniques to monitor the health of key enterprise application layers and of the resources they use, and to seamlessly restart or relocate application components after failures. In this paper, we first describe the manifold uses of HACs to protect essential layers of a critical application and present the architecture of high availability clusters. We then propose a taxonomy that covers all key aspects of HACs -- deployment patterns, application areas, types of cluster, topology, cluster management, failure detection and recovery, consistency and integrity, and data synchronisation; and we use this taxonomy to provide a comprehensive survey of the end-to-end software solutions available for the HAC deployment of enterprise applications. Finally, we discuss the limitations and challenges of existing HAC solutions, and we identify opportunities for future research in the area.