The ICREA "International Computer Room Experts Association" is a nonprofit International association formed by engineers in the design, construction, operation, management, maintenance, procurement, installation and auditing data centers. ICREA provides best practices for the design, construction, management, operation, maintenance, acquisition and installation of infrastructure for information technology environments.
The standard "ICREA-Std-131-2013" is a set of recommendations and best practices between countries and a group of experts in DPC that defines how to build a data center in accordance with the desired reliability and security levels as follows:
| Level | Description | Availability |
| I | Quality Assurance Data Center (QADC) | 95% |
| II | World Class Quality Assurance Data Center (WCQA) | 99% |
| III | Safety World Class Quality Assurance Data Center (S-WCQA) | 99.9% |
| IV | High Security World Class Quality Assurance Data Center (HS-WCQA) | 99.99% |
| V | High Security High Available World Class Quality Assurance Data Center (HSHA-WCQA) |
99.998% |
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.
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.
