Uptime Institute Tiers
The Uptime Institute created the standard Tier Classification System to evaluate various data center facilities in terms of potential site infrastructure performance, or uptime. Uptime Institute has not authorized other organizations to certify data centers under its Tier Classification System. Uptime Institute does not design, build or operate data centers.
How does AWS apply the Uptime Institute guidelines?
AWS operates our data centers in alignment with the Tier III+ guidelines, but we have chosen not to have a certified Uptime Institute based tiering level so that we have more flexibility to expand and improve performance. AWS' approach to infrastructure performance acknowledges the Uptime Institute's Tiering guidelines and applies them to our global data center infrastructure design to ensure the highest level of performance and availability for our customers. AWS then improves on the guidelines provided by the Uptime Institute to scale for global operations and produce an operating outcome for availability and performance that far exceeds that which would be achieved through the Uptime Institute tiering guidelines alone. Although we do not claim alignment with Tier 4, we can ensure that our systems have a fault tolerant sequence of operations with self-correcting mitigations in place.
How do AWS Availability Zones provide fault isolation?
AWS has identified critical system components required to maintain the availability of the system and recover service in the event of outage. Critical system components are backed up across multiple, isolated locations known as Availability Zones. Each Availability Zone runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable. Availability Zones are connected to each other with fast, private fiber-optic networking, enabling you to easily architect applications that automatically fail-over between Availability Zones without interruption.
Can customers achieve high availability on AWS?
Yes. AWS customers can build highly resilient systems in the cloud by employing multiple instances in multiple Availability Zones and data replication to achieve extremely high recovery time and recovery point objectives, as well as service availability of 99.999% and more. Service availability is therefore a function of the design; customers who care about the availability and performance of their applications want to deploy these applications across multiple Availability Zones in the same region for fault tolerance and low latency. Some AWS services, such as Amazon S3, are built to leverage all Availability Zones within the region and have a durability objective of 99.999999999%; they can be used for highly durable storage across Availability Zones and persistent volume (Amazon EBS) snapshots.