Best High Availability Cluster Solutions for Microsoft 365

Failover Clustering in Windows Server (and Azure Local) allows a collection of independent servers to collaborate, enhancing both availability and scalability for clustered roles, which were previously referred to as clustered applications and services. These interconnected nodes utilize a combination of hardware and software solutions, ensuring that if one node encounters a failure, another node seamlessly takes over its responsibilities through an automated failover mechanism. Continuous monitoring of clustered roles ensures that if they cease to function properly, they can be restarted or migrated to uphold uninterrupted service. Additionally, this feature includes support for Cluster Shared Volumes (CSVs), which create a cohesive, distributed namespace and enable reliable shared storage access across all nodes, thereby minimizing potential service interruptions. Common applications of Failover Clustering encompass high‑availability file shares, SQL Server instances, and Hyper‑V virtual machines. This functionality is available on Windows Server versions 2016, 2019, 2022, and 2025, as well as within Azure Local environments, making it a versatile choice for organizations looking to enhance their system resilience. By leveraging Failover Clustering, organizations can ensure their critical applications remain available even in the event of hardware failures.