SQL Server High-Availability: How and Why?
Blog post from Tessell
The guide outlines the procedure for setting up a high-availability (HA) configuration for Microsoft SQL Server using Windows Server Failover Clusters (WSFC) to ensure database robustness and minimize downtime. It details the configuration of nodes in different availability zones, including communication protocols and IP address management for Domain Independent Failover Cluster Groups, and emphasizes connectivity within an Active Directory environment for Active Directory Failover Clusters. The process involves installing a WSFC and configuring an Always-on Availability Group with automatic failover and synchronous commit modes. The guide describes failover scenarios where, in the event of a node failure, the secondary node takes over as the primary instance, ensuring service continuity. It also covers the patching process for maintaining high availability, which involves updating the failover instance first, executing a switchover, and then updating the previous primary node, thereby ensuring uninterrupted operations.