The reliability pillar has a number of crossovers with the operational excellence pillar. We live in a 24/7 world, and users expect applications to be available at all hours, running at full capacity. The reliability pillar of the AWS Well-Architected Framework focuses on techniques and practices that can help you achieve a zero-downtime infrastructure.
When we speak of reliability, be it uptime for a web server or the durability of saved data, we usually speak in terms of nines. For example, Amazon S3 offers a staggering 11 nines of durability for stored objects. That's 99.999999999% durability, which is made possible by storing redundant copies throughout a region in various Availability Zones (AZs). Several services offer SLAs ...
