Understanding high availability with Azure

High availability refers to an important aspect of a service or application that ensures uninterrupted operations by meeting or surpassing its promised service-level agreement (SLA). Users are guaranteed a certain SLA based on the service type. For instance, an SLA might guarantee 99% availability for an application over the course of a year. This means the service should be accessible to users for a minimum of 361.35 days out of the 365-day period. Failure to meet this availability requirement would be considered a breach of the SLA.

In the case of mission-critical applications, the high-availability SLA is often up to 99.999% for the year. This means the application is expected to run continuously and remain accessible throughout the entire year, with a maximum allowable downtime of only 5.2 hours. If the actual downtime exceeds the defined SLA threshold, users may be eligible for credit, which is calculated based on the overall uptime...